I am working on a game in OBJ C that has a ball view and a stage view. The stage view has 4 subviews. All views are UIImageViews. I have a method for collision detection that is working. I would like to expand it to more than 4 subviews without simply creating more lines of code. Looking at the code below, is there a way to simplify this into loops instead. Thanks!
// convert each square to be relevant to ball's superview in order to collision detect
CGRect square_01Frame = [ball.superview convertRect:square_01.frame fromView:square_01.superview];
CGRect square_02Frame = [ball.superview convertRect:square_02.frame fromView:square_02.superview];
CGRect square_03Frame = [ball.superview convertRect:square_03.frame fromView:square_03.superview];
CGRect square_04Frame = [ball.superview convertRect:square_04.frame fromView:square_04.superview];
// convert CGRects to NSStrings for storage in square_frames array
NSString *square_01FrameString = NSStringFromCGRect(square_01Frame);
NSString *square_02FrameString = NSStringFromCGRect(square_02Frame);
NSString *square_03FrameString = NSStringFromCGRect(square_03Frame);
NSString *square_04FrameString = NSStringFromCGRect(square_04Frame);
// load array of NSStrings
[square_frames replaceObjectAtIndex:0 withObject:square_01FrameString];
[square_frames replaceObjectAtIndex:1 withObject:square_02FrameString];
[square_frames replaceObjectAtIndex:2 withObject:square_03FrameString];
[square_frames replaceObjectAtIndex:3 withObject:square_04FrameString];
// create a for loop
for (int i=0; i<4; i++) { // 4 squares
// create test frame
CGRect test_frame = CGRectFromString([square_frames objectAtIndex:i]);
if (CGRectIntersectsRect(test_frame,ball.frame)) { // collision detection
// do something
}
}
Well, I would do a number of things.
First, I would create a ball "model", just an NSObject subclass to represent the Ball. Probably, that would have a property "location" or something, which is the CGRect.
Then, your current view could have an array of ball objects on the screen, and just loop through them.
Overall, though, I don't think using UIView's rects is the best way to manage collision detection. I think you'd be better off defining that in some other way, and then simply updating the UI accordingly.
Generally, it's not a good idea to rely on your UI implementation for game design. It makes it hard to change (as you note in your question).
Related
I am trying to find if collision occurs between two rectangles in objective-c. I thought one way to accomplish this would be detect the rectangle that is closest to 0,0 point then do rest of the work.
I wrote a function that takes two rectangle objects as parameters and does the math to calculate area, distance to origin etc....
So lets say rect1 is at (100,200) and rect1's width is 100 height 200, rect2 is at 150,150 and rect2's width is 100 height 200 this is calculated by function well enough.
If I switch rec1 and rect2 properties, so rect1 will be at 150,150 while rect2 will be at 100,200. And call following function
-(Rectangle*)intersect:(Rectangle*)rectA:(Rectangle*)rectB{
//check closest rectangle to 0,0 and switch rectangles
if (rectA.origin.x>rectB.origin.x) {
Rectangle *temporary = [[Rectangle alloc] init];
temporary=rectA;
rectA=rectB;
rectB=temporary;
[temporary release];
}
float rectAX = rectA.origin.x;
float rectAY = rectA.origin.y;
float rectBX = rectB.origin.x;
float rectBY = rectB.origin.y;
When I enable guard malloc and zombies I get following error:
-[Rectangle origin]: message sent to deallocated instance 0x100acffd0
As soon as rectA.origin.x; is called I get the error.
So Howcome rectA or rectB is deallocated? What is the correct way to switch two objects that has bunch of properties ?
There is a built in function for comparing CGRects CGRectIntersectsRect(rectA, rectB) that you can use to check your rectangle's frames :)
As far as your code for switching you have created a third object by allocing temporary. Then you set the temporary pointer at rectA and then you release rectA at the end since its pointing to temporary. Leaving the newly created object as a leak and then sending messages to the released rectA.
You don't really want to swap object pointers like that if you can help it in my experience. But if you absolutely have to and understand what's going on you could do it like this:
// Create copies of your objects
Rectangle *rectACopy = [rectA copy];
Rectangle *rectBCopy = [rectB copy];
// release the originals.
[rectA release];
[rectB release];
// Set your copies to the original pointers.
rectA = rectBCopy;
rectB = rectACopy;
NSCopying Protocol
First you need to implement the protocol.
#interface Rectangle : NSObject <NSCopying>
Then you need to create the new method. This will create a new object but with all the same values.
- (id)copyWithZone:(NSZone *)zone
{
id copy = [[[self class] alloc] init];
if (copy) {
// Copy NSObject based properties like UIViews, NSArrays, Subclassed objects.
[copy setObjectProperty:[self.objectProperty copy]];
// Set primitives like ints, CGRects, Bools.
[copy setPrimitiveProperty:self.primitiveProperty];
}
return copy;
}
You don't need to allocate a new object instance for temporary (and therefore you don't need to release it either). You are just taking your 2 existing pointers and switching them around. You're correct to use a 3rd variable (temporary) but you don't need to allocate any new space because you're not moving anything in memory, just swapping which variables point to the existing objects.
-(Rectangle*)intersect:(Rectangle*)rectA:(Rectangle*)rectB{
//check closest rectangle to 0,0 and switch rectangles
if (rectA.origin.x>rectB.origin.x) {
//Rectangle *temporary = [[Rectangle alloc] init]; // here you don't need to allocate as you are not using this object
// So use
Rectangle *temporary=rectA;
rectA=rectB;
rectB=temporary;
//[temporary release]; //you don't need this. Here you were releasing rectA not the temp rect that you allocated just below if, as you assign rectA to temporary
}
float rectAX = rectA.origin.x;
float rectAY = rectA.origin.y;
float rectBX = rectB.origin.x;
float rectBY = rectB.origin.y;
i got the following code:
test.image = [testArray lastObject];
test.animationImages = testArray;
test.animationDuration = 1;
test.animationRepeatCount = 1;
[test startAnimating];
I am sure that one day i read that it is possible to "rewind" an animation but i can't find that solution any more - is there a better solution than ordering (DESC) the array?
Thanks!
You can reverse the animation by accessing the reverseObjectEnumerator's objects:
testArray = [[testArray reverseObjectEnumerator] allObjects];
You can then pass that into the animation:
test.image = [testArray lastObject];
test.animationImages = [[testArray reverseObjectEnumerator] allObjects];
test.animationDuration = 1;
test.animationRepeatCount = 1;
[test startAnimating];
Or you could look into UIViewAnimationOptionAutoreverse, but i'm not sure that it's entirely what you're looking for.
You are using a UIImageView, which has limited animation possibilities. Reverting an animation is possible, but using the CoreAnimation based animations. You have two options, depending on the level of control you want on your anim.
keep using UIImageView, and do what max_ suggests: modifying the images array so that the animation ends up being played as you want (if you need to play it forward then backward, you could change the array further to obtain that effect. Each image would have to appear multiple times in the array to achieve this)
switch to CALayer animation. You would have to convert your array of UIImages to an array of CGImages, and create a CABasicAnimation operating on the content keypath of the layer. You would then have all the control you need, including the option to autoreverse the anim, because the animation object implements the CAMediaTiming protocol that allows that kind of stuff.
I've got a simple, single-column, view-based NSTableView with items in it that can be dragged to reorder them. During drag and drop, I'd like to make it so that a gap for the item-to-be-dropped opens up at the location under the mouse. GarageBand does something like this when you drag to reorder tracks (video here: http://www.screencast.com/t/OmUVHcCNSl). As far as I can tell, there's no built in support for this in NSTableView.
Has anyone else tried to add this behavior to NSTableView and found a good solution? I've thought of and tried a couple approaches without much success. My first thought was to double the height of the row under the mouse during a drag by sending -noteHeightOfRowsWithIndexesChanged: in my data source's -tableView:validateDrop:... method, then returning twice the normal height in -tableView:heightOfRow:. Unfortunately, best I can tell, NSTableView doesn't update its layout during drag and drop, so despite calling noteHeightOfRowsWithIndexesChanged:, the row height isn't actually updated.
Note that I'm using a view-based NSTableView, but my rows are not so complex that I couldn't move to a cell-based table view if doing so helped accomplish this. I'm aware of the easy, built-in ability to animate a gap for the dropped item after a drag is complete. I'm looking for a way to open a gap while the drag is in progress. Also, this is for an app to be sold in the Mac App Store, so it must not use private API.
EDIT: I've just filed an enhancement request with Apple requesting built in support for this behavior: http://openradar.appspot.com/12662624. Dupe if you'd like to see it too. Update: The enhancement I requested was implemented in OS X 10.9 Mavericks, and this behavior is now available using NSTableView API. See NSTableViewDraggingDestinationFeedbackStyleGap.
I feel bizarre for doing this, but there's an extremely thorough answer in the queue here that appears to have been deleted by its author. In it, they provided the correct links to a working solution, which I feel need to be presented as an answer for someone else to take and run with, inclusive of them if they desire to do so.
From the documentation for NSTableView, the following caveats are tucked away for row animation effects:
Row Animation Effects
Optional constant that specifies that the tableview will use a fade for row or column removal. The effect can be combined with any NSTableViewAnimationOptions constant.
enum {
NSTableViewAnimationEffectFade = 0x1,
NSTableViewAnimationEffectGap = 0x2,
};
Constants:
...
NSTableViewAnimationEffectGap
Creates a gap for newly inserted rows. This is useful for drag and drop animations that animate to a newly opened gap and should be used in the delegate method tableView:acceptDrop:row:dropOperation:.
Going through the example code from Apple, I find this:
- (void)_performInsertWithDragInfo:(id <NSDraggingInfo>)info parentNode:(NSTreeNode *)parentNode childIndex:(NSInteger)childIndex {
// NSOutlineView's root is nil
id outlineParentItem = parentNode == _rootTreeNode ? nil : parentNode;
NSMutableArray *childNodeArray = [parentNode mutableChildNodes];
NSInteger outlineColumnIndex = [[_outlineView tableColumns] indexOfObject:[_outlineView outlineTableColumn]];
// Enumerate all items dropped on us and create new model objects for them
NSArray *classes = [NSArray arrayWithObject:[SimpleNodeData class]];
__block NSInteger insertionIndex = childIndex;
[info enumerateDraggingItemsWithOptions:0 forView:_outlineView classes:classes searchOptions:nil usingBlock:^(NSDraggingItem *draggingItem, NSInteger index, BOOL *stop) {
SimpleNodeData *newNodeData = (SimpleNodeData *)draggingItem.item;
// Wrap the model object in a tree node
NSTreeNode *treeNode = [NSTreeNode treeNodeWithRepresentedObject:newNodeData];
// Add it to the model
[childNodeArray insertObject:treeNode atIndex:insertionIndex];
[_outlineView insertItemsAtIndexes:[NSIndexSet indexSetWithIndex:insertionIndex] inParent:outlineParentItem withAnimation:NSTableViewAnimationEffectGap];
// Update the final frame of the dragging item
NSInteger row = [_outlineView rowForItem:treeNode];
draggingItem.draggingFrame = [_outlineView frameOfCellAtColumn:outlineColumnIndex row:row];
// Insert all children one after another
insertionIndex++;
}];
}
I'm unsure if it's really this simple, but it's at least worth inspection and outright refutal if it doesn't meet your needs.
Edit: see this answer's comments for the steps followed to the right solution. The OP has posted a more complete answer, which should be referred to by anyone looking for solutions to the same problem.
Note: The behavior this question and answer describes are now available using built in API in NSTableView on OS X 10.9 Mavericks and later. See NSTableViewDraggingDestinationFeedbackStyleGap.
This answer may still be useful if this behavior is needed in an app targeting OS X 10.8 or earlier.
Original answer below:
I've implemented this now. My basic approach looks like this:
#interface ORSGapOpeningTableView : NSTableView
#property (nonatomic) NSInteger dropTargetRow;
#property (nonatomic) CGFloat heightOfDraggedRows;
#end
#implementation ORSGapOpeningTableView
#pragma mark - Dragging
- (NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)sender
{
NSInteger oldDropTargetRow = self.dropTargetRow;
NSDragOperation result = [super draggingUpdated:sender];
CGFloat imageHeight = [[sender draggedImage] size].height;
self.heightOfDraggedRows = imageHeight;
NSMutableIndexSet *changedRows = [NSMutableIndexSet indexSet];
if (oldDropTargetRow > 0) [changedRows addIndex:oldDropTargetRow-1];
if (self.dropTargetRow > 0) [changedRows addIndex:self.dropTargetRow-1];
[self noteHeightOfRowsWithIndexesChanged:changedRows];
return result;
}
- (void)draggingExited:(id<NSDraggingInfo>)sender
{
self.dropTargetRow = -1;
[self noteHeightOfRowsWithIndexesChanged:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, [self numberOfRows])]];
[super draggingExited:sender];
}
- (void)draggingEnded:(id<NSDraggingInfo>)sender
{
self.dropTargetRow = -1;
self.heightOfDraggedRows = 0.0;
self.draggedRows = nil;
[self noteHeightOfRowsWithIndexesChanged:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, [self numberOfRows])]];
}
- (BOOL)performDragOperation:(id<NSDraggingInfo>)sender
{
self.dropTargetRow = -1;
self.heightOfDraggedRows = 0.0;
self.draggedRows = nil;
[self noteHeightOfRowsWithIndexesChanged:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, [self numberOfRows])]];
return [super performDragOperation:sender];
}
// In my delegate and data source:
- (NSDragOperation)tableView:(NSTableView *)tableView validateDrop:(id<NSDraggingInfo>)info proposedRow:(NSInteger)row proposedDropOperation:(NSTableViewDropOperation)dropOperation
{
if (dropOperation == NSTableViewDropOn)
{
dropOperation = NSTableViewDropAbove;
[self.tableView setDropRow:++row dropOperation:dropOperation];
}
NSDragOperation result = [self.realDataSource tableView:tableView validateDrop:info proposedRow:row proposedDropOperation:dropOperation];
if (result != NSDragOperationNone)
{
self.tableView.dropTargetRow = row;
}
else
{
self.tableView.dropTargetRow = -1; // Don't open a gap
}
return result;
}
- (CGFloat)tableView:(NSTableView *)tableView heightOfRow:(NSInteger)row
{
CGFloat result = [tableView rowHeight];
if (row == self.tableView.dropTargetRow - 1 && row > -1)
{
result += self.tableView.heightOfDraggedRows;
}
return result;
}
Note that this is simplified code, not a verbatim copy/paste from my program. I actually ended up making this all contained within an NSTableView subclass that uses proxy delegate and data source objects so the code in data source/delegate methods above is actually inside the proxies' intercept of the calls to the real delegate and data source. That way, the real data source and delegate don't have to do anything special to get the gap opening behavior. Also, there's sometimes a little flakiness with the table view animations, and this doesn't work for drags above the first row (no gap is opened since there's no row to make taller). All in all, despite the room for further improvement, this approach works reasonably well.
I'd still like to try a similar approach, but insert a blank row (as Caleb suggested) instead of changing the row height.
As of Mac OS X 10.9 (Mavericks), there's a much easier solution to animating drag & drop in a NSTableView:
[aTableView setDraggingDestinationFeedbackStyle:NSTableViewDraggingDestinationFeedbackStyleGap];
The table view will automatically insert gaps with animation as a row is dragged which is much nicer than the old blue line insertion point method.
One way to accomplish what you're asking is to insert an empty row at the proposed drop point (that is, between the two nearest rows). It sounds like you've been looking at using NSTableViewAnimationEffectGap, which as you note is really meant for animating the insertion when the drop is accepted in -tableView:acceptDrop:row:dropOperation:.
Since you want to open up the gap before the user releases the mouse button to actually do the drop, you could instead insert a blank row using -insertRowsAtIndexes:withAnimation: from your table's -draggingUpdate: method and at the same time delete any blank row you previously inserted for this drag using -removeRowsAtIndexes:withAnimation:. Use NSTableViewAnimationSlideUp and NSTableViewAnimationSlideDown as the animations for these operations, as appropriate.
I know that cocos2d has scheduling callbacks to do nice things but when you need to use one CCAction (like CCMoveTo one) in order to move a sprite from position a to b, you do not have the ability to make small position arrangements to the sprite position for as long as the action is in effect.
The only possible way I found is by making a sub-class of CCMoveTo in order to check for obstacles and therefore provide some kind of movement to the left or right to a sprite that was moving from top to the bottom of the iPhone screen. The problem is that the sub-class does not have access to the parent class' instance variables (like the startPosition_ one) because they have not been declared as properties.
So I used the following snippet to overcome this situation but I wonder if I am doing something wrong...
- (void)myUpdate:(ccTime)time {
if(delegate && method_) {
NSNumber *num = (NSNumber *)[delegate performSelector:method_ withObject:ownTarget];
if(num) {
double xpos = [num doubleValue];
[num release];
CCMoveTo *parent = [super retain];
parent->startPosition_.x += xpos;
[parent release];
}
[super update:time];
}
Is it correct to retain/release the super-class? The "[super update:time];" at the bottom of the code will make the final positioning.
CCMoveTo *parent = [super retain];
Ouch! This statement makes absolutely no sense. It is the same as writing:
[self retain];
As for accessing the super class' instance variables: unless they're declared #private you can access them. I just checked: they're not #private. You should be able to write in your subclass:
startPosition_.x += xpos;
If that doesn't work make sure your class is really a subclass of CCMoveTo, and not some other class.
Finally, I'd like to say that actions are very limited when it comes to implementing gameplay. You're probably much better off to simply animate your game objects by modifying their position property every frame, based on a velocity vector. You have much more freedom over the position and position updates, and none of the side effects of actions such as a one-frame delay every time you run a new action.
-(void) update:(ccTime)delta
{
// modify velocity based on whatever you need, ie gravity, or just heading in one direction
// then update the node's position by adding the current velocity to move it:
self.position = CGPointMake(self.position.x + velocity.x, self.position.y + velocity.y);
}
I am making a simple game that requires that I draw multiple UIImages in many different places. My problem here is that I need to add the UIImages to an NSMutableArray, and access them later. Using NSStrings to represent the images (such as for paths) will not work here, so I need to know how to change the images for every UIImage in the array.
My code is as follows (at least, for accessing the NSMutableArray). The NSMutableArray is declared in my .h file, and is initialized in a different method.
for (int a = 0; a <= [theArray count]; a ++) {
// I make a UIImage, which I will draw later
UIImage *theImage = [theArray objectAtIndex:a];
// then I do the drawing
}
This works fine. My problem is that I cannot figure out how to change a particular object in the NSMutableArray. How can I do this?
By the way, I am adding the UIImages to the NSMutableArray with the following code.
+ (void) createCarWithImage:(NSString*)theImageName {
UIImage *anImage= [UIImage imageNamed:theImageName];
[theArray addObject:anImage];
}
I think you want to use this method:
- (void)replaceObjectAtIndex:(NSUInteger)index withObject:(id)anObject
e.g.:
[theArray replaceObjectAtIndex:4 withObject:someOtherImage];
Just modify each UIImage in the NSMutableArray as is, you only have a pointer to the actual data. That is, regardless of what pointer you use to change the data, the data is changed for every pointer.
Additionally, you can also iterate over your UIImages with:
for (UIImage *img in theArray)
{
//send messages to img
}
Answer to Comment
You can modify the UIImage at index 4 by:
UIImage *image = [theArray objectAtIndex:4];
//send messages to image