I was wondering if there is any way to get a more accurate version of the contentOffset, or estimate/calculate the contentOffset or (preferably) the first derivative of contentOffset of a UIScrollView. I am trying to perform an action when the rate of change of the contentOffset of my UIScrollView is very small, but 0.5f isn't quite precise enough.
Any help is greatly appreciated.
You can't get better precision than the one provided by contentOffset. You could calculate velocity using regular ds/dt equation:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
static CGFloat prevPos = 0.0; //you can store those in iVars
static NSTimeInterval prevTime = 0.0;
CGFloat newPos = scrollView.contentOffset.y;
NSTimeInterval newTime = [NSDate timeIntervalSinceReferenceDate];
double v = (newPos - prevPos)/(newTime - prevTime);
prevPos = newPos;
prevTime = newTime;
}
However, if you are feeling extremely hacky, and you want you code to be unsafe, you can peek into UIScrollView's velocity iVars directly by using this category
#interface UIScrollView(UnsafeVelocity)
- (double) unsafeVerticalVelocty;
#end
#implementation UIScrollView(UnsafeVelocity)
- (double) unsafeVerticalVelocty
{
double returnValue = 0.0;
id verticalVel = nil;
#try {
verticalVel = [self valueForKey:#"_verticalVelocity"];
}
#catch (NSException *exception) {
NSLog(#"KVC peek failed!");
}
#finally {
if ([verticalVel isKindOfClass:[NSNumber class]]) {
returnValue = [verticalVel doubleValue];
}
}
return returnValue;
}
#end
To get horizontal velocity replace _verticalVelocity with _horizontalVelocity. Notice, that the values you will get seem to be scaled differently. I repeat once more: while this is (probably) the best value of velocity you can get, it is very fragile and not future-proof.
Related
I have been using a similar method to as this:
https://github.com/oscardelben/CocoaNavigationGestures
To capture two finger swipes on the Mac, under Yosemite it is no longer working. Anyone know what has change, or what I need to change for this to work.
The accepted answer didn't work well for me - it would often not detect the swipe. Instead, I overrode wantsScrollEventsForSwipeTrackingOnAxis:(NSEventGestureAxis)axis to return YES for the appropriate axis, then overrode scrollWheel:(NSEvent *)theEvent to detect scrolling. Works perfect every time.
The complete answer in Swift 5.3, based on #bmuller would be:
override func wantsScrollEventsForSwipeTracking(on axis: NSEvent.GestureAxis) -> Bool {
return axis == .horizontal
}
override func scrollWheel(with event: NSEvent) {
if event.scrollingDeltaX < 0 {
print("Go forward")
}
else {
print("Go back")
}
}
Multiple swipe events might be sent in a single gesture with this code. You may need to add phase(NSEventPhase) handling code to the scrollWheel(...) function e.g.
override func scrollWheel(with event: NSEvent) {
guard event.phase == .began else {
return
}
if event.scrollingDeltaX < 0 {
print("Go forward")
}
else {
print("Go back")
}
}
On your Mac, go to system preferences and you will find all the different settings of the trackpad.
From here: https://discussions.apple.com/thread/5710582
Hope I helped.
This was my solution, seems to be working for me.
#define kSwipeMinimumLength 0.2
- (void)touchesBeganWithEvent:(NSEvent *)event{
if(event.type == NSEventTypeGesture){
NSSet *touches = [event touchesMatchingPhase:NSTouchPhaseAny inView:self];
if(touches.count == 2){
self.twoFingersTouches = [[NSMutableDictionary alloc] init];
for (NSTouch *touch in touches) {
[self.twoFingersTouches setObject:touch forKey:touch.identity];
}
}
}
}
- (void)touchesMovedWithEvent:(NSEvent*)event {
NSSet *touches = [event touchesMatchingPhase:NSTouchPhaseEnded inView:self];
if(touches.count > 0){
NSMutableDictionary *beginTouches = [self.twoFingersTouches copy];
self.twoFingersTouches = nil;
NSMutableArray *magnitudes = [[NSMutableArray alloc] init];
for (NSTouch *touch in touches)
{
NSTouch *beginTouch = [beginTouches objectForKey:touch.identity];
if (!beginTouch) continue;
float magnitude = touch.normalizedPosition.x - beginTouch.normalizedPosition.x;
[magnitudes addObject:[NSNumber numberWithFloat:magnitude]];
}
float sum = 0;
for (NSNumber *magnitude in magnitudes)
sum += [magnitude floatValue];
// See if absolute sum is long enough to be considered a complete gesture
float absoluteSum = fabsf(sum);
if (absoluteSum < kSwipeMinimumLength) return;
// Handle the actual swipe
// This might need to be > (i am using flipped coordinates), you can use an else to go forward also.
if (sum > 0){
NSLog(#"go back");
}
}
}
I've just started with the sparrow framework, and have been following "The Big Sparrow Tutorial" by Gamua themselves. I'm on the first part of the tutorial, using the AppScaffold 1.3 but when I try to compile my basic code it hangs at the loading screen and gives me a SIGABRT error.
I put an exception breakpoint, and it stopped here, in GameController.m (seen at bottom) of the AppScaffold:
mGame = [[Game alloc] initWithWidth:gameWidth height:gameHeight];
This was also my only output:
2012-07-30 07:19:54.787 AppScaffold[1682:10a03] -[Game initWithWidth:height:]: unrecognized selector sent to instance 0x7553980
(lldb)
I am using the stock AppScaffold, the only thing I changed was the Game.m.
This is my Game.m:
#interface Game : SPSprite
#end
#implementation Game
{
#private
SPImage *mBackground;
SPImage *mBasket;
NSMutableArray *mEggs;
}
- (id)init
{
if((self = [super init]))
{
//load the background image first, add it to the display tree
//and keep it for later use
mBackground = [[SPImage alloc] initWithContentsOfFile:#"background.png"];
[self addChild:mBackground];
//load the image of the basket, add it to the display tree
//and keep it for later use
mBasket = [[SPImage alloc] initWithContentsOfFile:#"basket.png"];
[self addChild:mBasket];
//create a list that will hold the eggs,
//which we will add and remove repeatedly during the game
mEggs = [[NSMutableArray alloc] init];
}
return self;
}
- (void)dealloc
{
[mBackground release];
[mBasket release];
[mEggs release];
[super dealloc];
}
#end
I've tried my best to use my basic troubleshooting tactics, but I'm very new to Obj-C and Sparrow and could use a hand :)
Thanks
EDIT: I've addded the GameController.m contents here for clarity:
//
// GameController.m
// AppScaffold
//
#import <OpenGLES/ES1/gl.h>
#import "GameController.h"
#interface GameController ()
- (UIInterfaceOrientation)initialInterfaceOrientation;
#end
#implementation GameController
- (id)initWithWidth:(float)width height:(float)height
{
if ((self = [super initWithWidth:width height:height]))
{
float gameWidth = width;
float gameHeight = height;
// if we start up in landscape mode, width and height are swapped.
UIInterfaceOrientation orientation = [self initialInterfaceOrientation];
if (UIInterfaceOrientationIsLandscape(orientation)) SP_SWAP(gameWidth, gameHeight, float);
mGame = [[Game alloc] initWithWidth:gameWidth height:gameHeight];
mGame.pivotX = gameWidth / 2;
mGame.pivotY = gameHeight / 2;
mGame.x = width / 2;
mGame.y = height / 2;
[self rotateToInterfaceOrientation:orientation animationTime:0];
[self addChild:mGame];
}
return self;
}
- (void)dealloc
{
[mGame release];
[super dealloc];
}
- (UIInterfaceOrientation)initialInterfaceOrientation
{
// In an iPhone app, the 'statusBarOrientation' has the correct value on Startup;
// unfortunately, that's not the case for an iPad app (for whatever reason). Thus, we read the
// value from the app's plist file.
NSDictionary *bundleInfo = [[NSBundle mainBundle] infoDictionary];
NSString *initialOrientation = [bundleInfo objectForKey:#"UIInterfaceOrientation"];
if (initialOrientation)
{
if ([initialOrientation isEqualToString:#"UIInterfaceOrientationPortrait"])
return UIInterfaceOrientationPortrait;
else if ([initialOrientation isEqualToString:#"UIInterfaceOrientationPortraitUpsideDown"])
return UIInterfaceOrientationPortraitUpsideDown;
else if ([initialOrientation isEqualToString:#"UIInterfaceOrientationLandscapeLeft"])
return UIInterfaceOrientationLandscapeLeft;
else
return UIInterfaceOrientationLandscapeRight;
}
else
{
return [[UIApplication sharedApplication] statusBarOrientation];
}
}
- (void)rotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
animationTime:(double)animationTime
{
float angles[] = {0.0f, 0.0f, -PI, PI_HALF, -PI_HALF};
float oldAngle = mGame.rotation;
float newAngle = angles[(int)interfaceOrientation];
// make sure that rotation is always carried out via the minimal angle
while (oldAngle - newAngle > PI) newAngle += TWO_PI;
while (oldAngle - newAngle < -PI) newAngle -= TWO_PI;
// rotate game
if (animationTime)
{
SPTween *tween = [SPTween tweenWithTarget:mGame time:animationTime
transition:SP_TRANSITION_EASE_IN_OUT];
[tween animateProperty:#"rotation" targetValue:newAngle];
[[SPStage mainStage].juggler removeObjectsWithTarget:mGame];
[[SPStage mainStage].juggler addObject:tween];
}
else
{
mGame.rotation = newAngle;
}
// inform all display objects about the new game size
BOOL isPortrait = UIInterfaceOrientationIsPortrait(interfaceOrientation);
float newWidth = isPortrait ? MIN(mGame.gameWidth, mGame.gameHeight) :
MAX(mGame.gameWidth, mGame.gameHeight);
float newHeight = isPortrait ? MAX(mGame.gameWidth, mGame.gameHeight) :
MIN(mGame.gameWidth, mGame.gameHeight);
if (newWidth != mGame.gameWidth)
{
mGame.gameWidth = newWidth;
mGame.gameHeight = newHeight;
SPEvent *resizeEvent = [[SPResizeEvent alloc] initWithType:SP_EVENT_TYPE_RESIZE
width:newWidth height:newHeight animationTime:animationTime];
[mGame broadcastEvent:resizeEvent];
[resizeEvent release];
}
}
// Enable this method for the simplest possible universal app support: it will display a black
// border around the iPhone (640x960) game when it is started on the iPad (768x1024); no need to
// modify any coordinates.
/*
- (void)render:(SPRenderSupport *)support
{
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
{
glEnable(GL_SCISSOR_TEST);
glScissor(64, 32, 640, 960);
[super render:support];
glDisable(GL_SCISSOR_TEST);
}
else
[super render:support];
}
*/
#end
Here is my Xcode project: http://cl.ly/2e3g02260N47
You are calling a
initWithWidth:height:
method, while none is defined in your class.
From your edit, it seems that the initWithWidth method is declared in the class GameController, not in Game.
So, it seems that the
In which context are you calling initWithWidth:height: method is declared in Game.h but you define it in GameController.m.
This explains both why you get the SIGABRT and the errors when compiling.
The fix is calling
mGame = [[GameController alloc] init];
from GameController initWithWidth...
- (id)initWithWidth:(float)width height:(float)height
{
if ((self = [super initWithWidth:width height:height]))
{
float gameWidth = width;
float gameHeight = height;
// if we start up in landscape mode, width and height are swapped.
UIInterfaceOrientation orientation = [self initialInterfaceOrientation];
if (UIInterfaceOrientationIsLandscape(orientation)) SP_SWAP(gameWidth, gameHeight, float);
mGame = [[Game alloc] init];
mGame.pivotX = gameWidth / 2;
mGame.pivotY = gameHeight / 2;
mGame.x = width / 2;
mGame.y = height / 2;
[self rotateToInterfaceOrientation:orientation animationTime:0];
[self addChild:mGame];
}
return self;
}
The tutorial was very old and was incompatible with the latest scaffold;
I did this:
- (id)init
{
if((self = [super init]))
{
when I should've done this:
- (id)initWithWidth:(float)width height:(float)height
{
if ((self = [super initWithWidth:width height:height]))
{
thanks, though sergio!
(There are much better sparrow tutorials and I'm even making my own video tutorials :P)
[Edit: Rectangle definition added at bottom.]
[Edit2: XYPoint interface added at bottom.]
I'm working on a method that checks if two rectangles overlap. (Yeah, I'm in Kochan's Programming in Objective-C, doing the exercises, and I am painfully new at this.) When I compile this, the error message is: "Invalid operands to binary +". I get it on the first if statement and on the if-else that follows it.
I think I have an issue with pointers, but Kochan doesn't talk about this much.
And, if I take out these lines, the rest of the method works just fine. And the relevant variables are all floating type.
Help?
Also, any other thoughts on the method would be totally welcome. (Like, how do I make lines of code not go out so long. Like I said, painfully new at this.)
-(void) overlap: (Rectangle *)r2
{
overlapRectangle = [[Rectangle alloc] init];
leftRectangle = [[Rectangle alloc] init];
rightRectangle = [[Rectangle alloc] init];
lowerRectangle = [[Rectangle alloc] init];
upperRectangle = [[Rectangle alloc] init];
BOOL xIntersect = NO;
BOOL yIntersect = NO;
// Test to see if the Rectangle contains, or is equal to, Rectangle b
if (origin.x <= r2.origin.x && origin.y <= r2.origin.y && (origin.x + width) >= (r2.origin + r2.width) && (origin.y + height) >= (r2.origin.y + r2.height) )
{
overlapRectangle = r2;
}
// Test to see if Retangle b contains, or is equal to, the Rectangle
else if (origin.x >= r2.origin.x && origin.y >= r2.origin.y && origin.x + width <= r2.origin + r2.width && origin.y + height <= r2.origin.y + r2.height )
{
overlapRectangle = self;
}
// I should add tests for triangles overlapping on three
// sides or overlapping on two sides, but I'm not going
// to right now. Just learning objects and methods.
// Test to see if rectangles overlap on the x-axis
// Current is an if, because I wanted to run the code below
// to see if it worked, and it did.
if (origin.x <= r2.origin.x)
{
leftRectangle = self;
rightRectangle = r2;
}
else
{
rightRectangle = self;
leftRectangle = r2;
}
if (rightRectangle.origin.x + rightRectangle.width > leftRectangle.origin.x)
{
xIntersect = YES;
}
// Test to see if rectangles overlap on the y-axis
if (origin.y <= r2.origin.y)
{
lowerRectangle = self;
upperRectangle = r2;
}
else
{
lowerRectangle = self;
upperRectangle = r2;
}
if (lowerRectangle.origin.y + lowerRectangle.height > upperRectangle.origin.y)
{
yIntersect = YES;
}
// If retangles overlap on both the x-axis and y-axis,
// determination of overlapping rectangle's origin, height, and width
// and display same.
if (xIntersect == YES && yIntersect == YES)
{
overlapRectangle.origin.y = upperRectangle.origin.y;
overlapRectangle.origin.x = rightRectangle.origin.x;
overlapRectangle.height = lowerRectangle.height - (upperRectangle.origin.y - lowerRectangle.origin.y);
overlapRectangle.width = leftRectangle.width - (rightRectangle.origin.x - leftRectangle.origin.x);
NSLog (#"Your rectangles overlap.");
NSLog (#"Rectangle: w = %g, h = %g", overlapRectangle.width, overlapRectangle.height);
NSLog (#"Area = %g, Perimeter = %g", [overlapRectangle area], [overlapRectangle perimeter]);
NSLog (#"Origin at (%g, %g)", overlapRectangle.origin.x, overlapRectangle.origin.y);
}
else
{
NSLog (#"Your rectangles do not overlap.");
}
[overlapRectangle autorelease];
[leftRectangle autorelease];
[rightRectangle autorelease];
[lowerRectangle autorelease];
[upperRectangle autorelease];
}
Rectangle Definition:
// Interface, Rectangle Class
#interface Rectangle : NSObject
{
float width;
float height;
XYPoint *origin;
// For overlapping calculations
Rectangle *overlapRectangle;
Rectangle *leftRectangle;
Rectangle *rightRectangle;
Rectangle *lowerRectangle;
Rectangle *upperRectangle;
}
#property float width, height;
-(XYPoint *) origin;
-(void) setOrigin: (XYPoint *) pt;
-(void) setWidth: (float) w andHeight: (float) h;
-(float) area;
-(float) perimeter;
-(void) print;
-(void) translate;
-(void) overlap: (Rectangle *)r2;
-(void) draw;
#end
XYPoint interface:
#import <Foundation/Foundation.h>
#interface XYPoint : NSObject
{
float x;
float y;
}
#property float x, y;
-(void) setX: (float) xVal andY: (float) yVal;
#end
You've just got what is probably a typo:
// Test to see if the Rectangle contains, or is equal to,
// Rectangle b
if (origin.x <= r2.origin.x && origin.y <= r2.origin.y &&
(origin.x + width) >= (r2.origin + r2.width) &&
//^^^This is trying to add an XYPoint,
// which is an object, to a float.
(origin.y + height) >= (r2.origin.y + r2.height) )
{
overlapRectangle = r2;
}
// Test to see if Rectangle b contains, or is equal to,
// the Rectangle
else if (origin.x >= r2.origin.x && origin.y >= r2.origin.y &&
origin.x + width <= r2.origin + r2.width &&
//^^^Same thing.
origin.y + height <= r2.origin.y + r2.height )
{
...
The compiler should have told you what the types were that you were asking to be added:
error: invalid operands to binary + (have 'struct XYPoint *' and 'float')
that's the key. You just need to change the r2.origin to r2.origin.x so that you're adding two floats.
As for the length of the lines, there's two things you can do. You can move each segment of the conditions to different lines as I've done, but it would probably be best to create a couple of methods for Rectangle that will do the tests for you. This will make the code more readable, so when you come back to it in six months and the line reads:
if( [self containsRectangle:r2] || [self isEqualToRectangle:r2] ){
you'll know what's going on right away. Here's some suggestions for that:
- (BOOL)containsRectangle:(Rectangle *)otherRect {
BOOL originBelow = ((origin.x <= otherRect.origin.x) &&
(origin.y <= otherRect.origin.y));
float maxX = origin.x + width;
float otherMaxX = otherRect.origin.x + otherRect.width;
BOOL maxXGreater = maxX >= otherMaxX;
Bfloat maxY = origin.y + height;
float otherMaxY = otherRect.origin.y + otherRect.height;
BOOL maxYGreater = maxY >= otherMaxY;
return originBelow && maxXGreater && maxYGreater;
}
- (BOOL)isEqualToRectangle:(Rectangle *)otherRect {
BOOL sizeEqual = ((width == otherRect.width) &&
(height == otherRect.height));
return sizeEqual && [origin isEqualToXYPoint:otherRect.origin];
}
Note: I didn't test these, just pasted them together from the conditions of your ifs, so double-check them before you use them. I did fix the typo, though.
Notice that I also made up a method on XYPoint here, isEqualToXYPoint:; you can implement that as well, to return a BOOL if the x and y of both XYPoints are equal.
I am working with MKMapView Based application. I need a clarification whether it is possible to eliminate the pin OverLap in the MKMapView? Because at some places there are large number of pins displaying. It is difficult to me to identify the pins.
If you have an Apple Developer Account, I would strongly recommend getting the Session 111 video from the 2011 WWDC Conference Sessions, entitled "Visualizing Information Geographically with MapKit". One of the segments specifically covers how to cluster content from large data sets to allow you to group or ungroup pins based on density at various zoom levels.
Their example is elegantly simple, but at the heart of the problem you want to replace a group of overlapping pins with a single pin and as you zoom in the single pin will split back into the individual pins.
How and when you decide to group things can be varied considerably. Apple's solution simply subdivides the map into a grid and any box that has more than 1 pin results in a group. You could also take an algorithmic approach such as using a kMeansCluster algorithm which is incredibly simple and you could feed all of your annotations through the algorithm and get an array of groups out the other side logically organized.
From there it's a matter of keeping track of all the individual pins and how they are grouped as you zoom in and out. You will only display a single annotation for each group or any individual pins that are left over. It's also possible to animate the transitions as the map zooms in and out so you can visually reinforce what is happening.
My own technique is too closely related to Apple's approach for me to post here so I'm hoping you can access the above video which covers almost all of these points.
For this you have to implement clustering concept to your map.By using Apple demo code it's easy to implement clustering concept in our code. Reference link
Simply we can use following code for the Clustering
Steps to implement clustering
Step1 : The important thing is for clustering we use two mapviews(allAnnotationsMapView, ), One is for reference(allAnnotationsMapView).
#property (nonatomic, strong) MKMapView *allAnnotationsMapView;
#property (nonatomic, strong) IBOutlet MKMapView *mapView;
In viewDidLoad
_allAnnotationsMapView = [[MKMapView alloc] initWithFrame:CGRectZero];
Step2 : Add all annotations to the _allAnnotationsMapView, In below _photos are the annotations array.
[_allAnnotationsMapView addAnnotations:_photos];
[self updateVisibleAnnotations];
Step3 : Add below methods for clustering, in this PhotoAnnotation is the custom annotation.
MapViewDelegate methods
- (void)mapView:(MKMapView *)aMapView regionDidChangeAnimated:(BOOL)animated {
[self updateVisibleAnnotations];
}
- (void)mapView:(MKMapView *)aMapView didAddAnnotationViews:(NSArray *)views {
for (MKAnnotationView *annotationView in views) {
if (![annotationView.annotation isKindOfClass:[PhotoAnnotation class]]) {
continue;
}
PhotoAnnotation *annotation = (PhotoAnnotation *)annotationView.annotation;
if (annotation.clusterAnnotation != nil) {
// animate the annotation from it's old container's coordinate, to its actual coordinate
CLLocationCoordinate2D actualCoordinate = annotation.coordinate;
CLLocationCoordinate2D containerCoordinate = annotation.clusterAnnotation.coordinate;
// since it's displayed on the map, it is no longer contained by another annotation,
// (We couldn't reset this in -updateVisibleAnnotations because we needed the reference to it here
// to get the containerCoordinate)
annotation.clusterAnnotation = nil;
annotation.coordinate = containerCoordinate;
[UIView animateWithDuration:0.3 animations:^{
annotation.coordinate = actualCoordinate;
}];
}
}
}
clustering Handling methods
- (id<MKAnnotation>)annotationInGrid:(MKMapRect)gridMapRect usingAnnotations:(NSSet *)annotations {
// first, see if one of the annotations we were already showing is in this mapRect
NSSet *visibleAnnotationsInBucket = [self.mapView annotationsInMapRect:gridMapRect];
NSSet *annotationsForGridSet = [annotations objectsPassingTest:^BOOL(id obj, BOOL *stop) {
BOOL returnValue = ([visibleAnnotationsInBucket containsObject:obj]);
if (returnValue)
{
*stop = YES;
}
return returnValue;
}];
if (annotationsForGridSet.count != 0) {
return [annotationsForGridSet anyObject];
}
// otherwise, sort the annotations based on their distance from the center of the grid square,
// then choose the one closest to the center to show
MKMapPoint centerMapPoint = MKMapPointMake(MKMapRectGetMidX(gridMapRect), MKMapRectGetMidY(gridMapRect));
NSArray *sortedAnnotations = [[annotations allObjects] sortedArrayUsingComparator:^(id obj1, id obj2) {
MKMapPoint mapPoint1 = MKMapPointForCoordinate(((id<MKAnnotation>)obj1).coordinate);
MKMapPoint mapPoint2 = MKMapPointForCoordinate(((id<MKAnnotation>)obj2).coordinate);
CLLocationDistance distance1 = MKMetersBetweenMapPoints(mapPoint1, centerMapPoint);
CLLocationDistance distance2 = MKMetersBetweenMapPoints(mapPoint2, centerMapPoint);
if (distance1 < distance2) {
return NSOrderedAscending;
} else if (distance1 > distance2) {
return NSOrderedDescending;
}
return NSOrderedSame;
}];
PhotoAnnotation *photoAnn = sortedAnnotations[0];
NSLog(#"lat long %f %f", photoAnn.coordinate.latitude, photoAnn.coordinate.longitude);
return sortedAnnotations[0];
}
- (void)updateVisibleAnnotations {
// This value to controls the number of off screen annotations are displayed.
// A bigger number means more annotations, less chance of seeing annotation views pop in but decreased performance.
// A smaller number means fewer annotations, more chance of seeing annotation views pop in but better performance.
static float marginFactor = 2.0;
// Adjust this roughly based on the dimensions of your annotations views.
// Bigger numbers more aggressively coalesce annotations (fewer annotations displayed but better performance).
// Numbers too small result in overlapping annotations views and too many annotations on screen.
static float bucketSize = 60.0;
// find all the annotations in the visible area + a wide margin to avoid popping annotation views in and out while panning the map.
MKMapRect visibleMapRect = [self.mapView visibleMapRect];
MKMapRect adjustedVisibleMapRect = MKMapRectInset(visibleMapRect, -marginFactor * visibleMapRect.size.width, -marginFactor * visibleMapRect.size.height);
// determine how wide each bucket will be, as a MKMapRect square
CLLocationCoordinate2D leftCoordinate = [self.mapView convertPoint:CGPointZero toCoordinateFromView:self.view];
CLLocationCoordinate2D rightCoordinate = [self.mapView convertPoint:CGPointMake(bucketSize, 0) toCoordinateFromView:self.view];
double gridSize = MKMapPointForCoordinate(rightCoordinate).x - MKMapPointForCoordinate(leftCoordinate).x;
MKMapRect gridMapRect = MKMapRectMake(0, 0, gridSize, gridSize);
// condense annotations, with a padding of two squares, around the visibleMapRect
double startX = floor(MKMapRectGetMinX(adjustedVisibleMapRect) / gridSize) * gridSize;
double startY = floor(MKMapRectGetMinY(adjustedVisibleMapRect) / gridSize) * gridSize;
double endX = floor(MKMapRectGetMaxX(adjustedVisibleMapRect) / gridSize) * gridSize;
double endY = floor(MKMapRectGetMaxY(adjustedVisibleMapRect) / gridSize) * gridSize;
// for each square in our grid, pick one annotation to show
gridMapRect.origin.y = startY;
while (MKMapRectGetMinY(gridMapRect) <= endY) {
gridMapRect.origin.x = startX;
while (MKMapRectGetMinX(gridMapRect) <= endX) {
NSSet *allAnnotationsInBucket = [self.allAnnotationsMapView annotationsInMapRect:gridMapRect];
NSSet *visibleAnnotationsInBucket = [self.mapView annotationsInMapRect:gridMapRect];
// we only care about PhotoAnnotations
NSMutableSet *filteredAnnotationsInBucket = [[allAnnotationsInBucket objectsPassingTest:^BOOL(id obj, BOOL *stop) {
return ([obj isKindOfClass:[PhotoAnnotation class]]);
}] mutableCopy];
if (filteredAnnotationsInBucket.count > 0) {
PhotoAnnotation *annotationForGrid = (PhotoAnnotation *)[self annotationInGrid:gridMapRect usingAnnotations:filteredAnnotationsInBucket];
[filteredAnnotationsInBucket removeObject:annotationForGrid];
// give the annotationForGrid a reference to all the annotations it will represent
annotationForGrid.containedAnnotations = [filteredAnnotationsInBucket allObjects];
[self.mapView addAnnotation:annotationForGrid];
for (PhotoAnnotation *annotation in filteredAnnotationsInBucket) {
// give all the other annotations a reference to the one which is representing them
annotation.clusterAnnotation = annotationForGrid;
annotation.containedAnnotations = nil;
// remove annotations which we've decided to cluster
if ([visibleAnnotationsInBucket containsObject:annotation]) {
CLLocationCoordinate2D actualCoordinate = annotation.coordinate;
[UIView animateWithDuration:0.3 animations:^{
annotation.coordinate = annotation.clusterAnnotation.coordinate;
} completion:^(BOOL finished) {
annotation.coordinate = actualCoordinate;
[self.mapView removeAnnotation:annotation];
}];
}
}
}
gridMapRect.origin.x += gridSize;
}
gridMapRect.origin.y += gridSize;
}
}
By following above steps we can achieve clustering on mapview, it is not necessary to use any third party code or framework. Please check the Apple sample code here. Please let me know if you have any doubts on this.
It's quite easy to implement your own annotation clustering framework. Here's an example of a basic one that you can refer here.
If your pins are overlapping then it must be that your zoom level is high for that place.
You can think of removing some annotations in that zoom level until you dont have annotation overlaps and while zooming in you can add the annotations so that there are enough space between the annotations.
I'm doing the challenge exercises in Aaron Hillegass' book Cocoa Programming for Mac.
What I'm trying to do is have a window resize to twice the height of the width. Here is my code so far.
#import "AppController.h"
#implementation AppController
-(id) init
{
[super init];
NSLog(#"init");
[window setDelegate:self];
return self;
}
-(NSSize) windowWillResize:(NSWindow*) sender
toSize:(NSSize)frameSize
{
int x;
NSSize mySize;
mySize.width = x;
mySize.height = 2*x;
NSLog(#"mySize is %f wide and %f tall",mySize.width,mySize.height);
return mySize;
}
This does not work as intended I'm sure I'm not using the NSSize type correctly. I don't know a lot of C so using the struct is where I think I'm making my mistake.
ADDENDUM: I changed the above code to the following.I know that I'm being passed an NSSize so there is no reason to create another one (i.e. mySize).However, I don't understand why this works. Can someone explain.
#import "AppController.h"
#implementation AppController
-(id) init
{
[super init];
NSLog(#"init");
[window setDelegate:self];
return self;
}
-(NSSize) windowWillResize:(NSWindow*) sender
toSize:(NSSize)frameSize
{
//float x = 100;
//NSSize mySize;
//mySize.width = x;
//mySize.height = x * 2;
//NSLog(#"mySize is %f wide and %f tall",mySize.width,mySize.height);
NSLog(#"mySize is %f wide and %f tall",frameSize.width,frameSize.height);
return NSMakeSize(frameSize.width, frameSize.width * 2);
}
#end
Let's think about what you want mySize to be.
You want its width to be the same as frameSize.width
You want its height to be frameSize.width * 2.
Now let's look at what you do with x:
You set mySize.width to be equal to it
You set mySize.height to be x * 2
From this we can conclude:
You want to set x to frameSize.width.
Alternatively, the entire method could just be return NSMakeSize(frameSize.width, frameSize.width * 2).
You should assign an initial value to x:
int x = 100;
Otherwise, outcome is undefined.