I am creating custom UIImageViews and placing on a UIImageView in a UIScrollView. When the user taps on the custom UIImageView, it presents a popover.
The issue i may have is if two of the custom UIImageViews are overlapping. I need to ask the user which one he wants.
how can i tell which custom UIImageViews are within a tap? I need each view to return itself if it detects a tap. If more then one view returns, then i can ask the user which one he wants.
each custom UIImageView has a UITapGestureRecognizer created:
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(select)];
singleTap.numberOfTapsRequired = 1;
singleTap.delegate = self;
[self addGestureRecognizer:singleTap];
right now, only the top most custom UIImageView is getting the tap and displaying the popover.
I'm not sure how you planned on identifying which image was which, but for this example I've used tags. The following will receive the location of a touch within the scroll view, and compare that point to frames of the image views in the scrollviews subviews. It will then add the tags of the images that matched to a mutable array.
NOTE: If you don't empty this array when you dismiss the alert new objects will be continuously added to it.
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:myScrollView];
for (UIImageView *myImageView in myScrollView.subviews) {
if (CGRectContainsPoint(myImageView.frame, location)) {
[someMutableArray addObject:[NSNumber numberWithInteger:myImageView.tag]];
}
}
}
I assume by your question that the views are transparent so the user can see that in fact there is overlap, and may intentionally tap the area of overlap.
In any case what you need to do in this case is get the location of the tap:
[tapGesture locationInView:scrollView]
Then walk the scrollView's subView array, getting each of your UIImageView's, getting its frame, and seeing if the tap is inside that frame.
Now you have an array of possible images - you can pop an action sheet (whatever) and ask the user which to show.
Related
I have made a graph with data in a UIView called HeartrateGraph. In a UIViewController named HRGraphInfo, I have a connected label that should output values when the graph is touched. The problem is, I don't know how to send a touched event using delegates from the UIView to the UIViewController.
Here is my touch assignment code in the UIView:
UITouch *touch = [touches anyObject];
CGPoint point = [touch locationInView:self];
for (int i = 0; i < kNumberOfPoints; i++)
{
if (CGRectContainsPoint(touchAreas[i], point))
{
graphInfoRF.heartRateGraphString = [NSString stringWithFormat:#"Heart Rate reading #%d at %# bpm",i+1, dataArray[i]];
graphInfoRF.touched = YES;
break;
}
}
This segment of code is in a touchesBegan and properly stores the data value and number in the object graphInfoRF (I just did not show the declarations of dataArray, kNumberOfPoints, etc).
I am able to access graphInfoRF in the UIViewController using:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if (graphInfoRF.touched == YES) {
self.heartRateLabel.text = graphInfoRF.heartRateGraphString;
}
else {
self.heartRateLabel.text = #"No data got over to this file";}
}
The label will show the correct string, but only after the data point on the graph is touched AND the label is touched right after. How do I change the touchesBegan so that once I touch the data point on the graph it will fill the label with the data automatically without the need for a second and separate touch on the label?
All ViewControllers comes with a single view it manages once it's initialized. You should be familiar with this view, you see it whenever you use a ViewController in the Interface Builder and you can access it using self.view if you're modifying a subclass.
Since ViewControllers come with a view, it also receives touch events for that view. Implementing touchesBegan in the ViewController will then receive events for that view, and normally any subviews that view is managing. Since you've down your own implementation of 'touchesBegan' in your HeartRateGraph, and since HeartRateGraph is a subview of ViewControllers main view, HeartRateGraph will receive and handle the touch event first before the ViewController ever has a chance to receive and handle the event like it normally would (think of bubbling up).
So what's happening is, the code to change the label in ViewController is only called when the label is touched because the label is a subview of the ViewController's main view... and also label doesn't have its own touches implementation, so ViewController and is able to retrieve and handle the event the way you want only when you click somewhere outside the graph. If you understand then there are two ways to solve this.
Either pass the event up to your superview
[self.superview touchesBegan:touches withEvent:eventargs];
or the proper recommended way of doing it:
Protocols and Delegates where your View makes a delegate call to it ViewController letting it know the graph has been touched and the ViewController needs to update its contents
I have an iPad project structured with a UISplitViewController:
RootViewController
DetailviewController
Both of them are detecting touches with Gesture Recognizer inside their own Class.
I would like to create a transparent UIView on top of all the Classes to detect ONLY a Diagonal Swipe (from the left bottom corner to the right top corner).
So, when the swipe will be detected I will launch a function otherwise nothing appended and the touch should be passed on the low level view.
I tried these two solutions:
Add a GestureRecognizer on this top transparent view but this will hide all touches to the lower hierarchy views.( with userInteraction enabled: YES ofcourse);
The other solution is to make the init like this
-(id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
[self setBackgroundColor:[UIColor colorWithWhite:1 alpha:0.01]];
[self setUserInteractionEnabled:NO];
}
return self;
}
and try to detect the swipe with
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
But at this point all the touches are not detected.
Anybody have a nice solution?
I will not create a transparent UIView like you are mentioning. I will add a UISwipeGestureRecognizer to the UISplitViewController's view this is already the view that contains all your subviews. You can have access to the view within the app delegate:
UISplitViewController *splitViewController = (UISplitViewController *)self.window.rootViewController;
// attach the swipe gesture to the view that embeds the rootView and the detailView
UISwipeGestureRecognizer* swipeGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:splitViewController.view action:#selector(swipeUpdated:)];
Can't you just add a gesture recognizer to the UISplitViewController's view?
You should look into Container Controllers. You can make your own SplitViewController and make a third view on top of the controller that detects the swipe. Custom container controllers are pretty straight forward and gives you a lot of flexibility.
I have a UIScrollView with some UIViews in it.
What I am trying to do, is catch the touches events when the UIViews are touched/untouched.
The problem I am having, is the UIScrollView seems to swallow all the touch events, especially if you hold for too long on a UIView.
I preferably want the UIScrollView to have userInteraction disabled as it scrolls automatically.
Is this possible?
I have tried subclassing the UIViews but the touches events are never called in it.
You can attach a tapGesture to your scrollview with something along those lines:
UITapGestureRecognizer* tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapGestureUpdated:)];
tapGesture.delegate = self;
tapGesture.numberOfTapsRequired = 1;
tapGesture.numberOfTouchesRequired = 1;
[self addGestureRecognizer:_tapGesture];
then in your - (void)tapGestureUpdated:(UITapGestureRecognizer *)tapGesture method this is your responsability to determine the location of the touch and find out if there was a picking on one of your subviews. You could call then a method on a delegate that notify that a specific view has been touched.
Perhaps reordering your views so that a view that has a touch recognizer object associated with it is what the app recognizes. Move it in the document outline to the top (scroll view)
in my app, when the user touches on the view ,i am showing an UIImageView there and i drag and
drop the image from another UIImageView to that touched UIImageView.
But the problem is that, only the recent touched UIImageView is activated. i mean ,when i
click 3 times then shows 3 UIImageViews but only the last is activated and accept the another
image.
How can i make all touched UIImageViews are activated .. Any body help on this..
Thanks in advance.
You should read Apples documentation on the responder chain and event handling. The key UIView method here is
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
This method traverses the view hierarchy by sending the
pointInside:withEvent: message to each subview to determine which
subview should receive a touch event. If pointInside:withEvent:
returns YES, then the subview’s hierarchy is traversed; otherwise, its
branch of the view hierarchy is ignored. You rarely need to call this
method yourself, but you might override it to hide touch events from
subviews.
You should try this:
Where there is your UIView (Or a view):
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:#selector(tapped:)];
tapGesture.numberOfTapsRequired = 1;//number of tap
[view addGestureRecognizer:tapGesture];
The selector:
-(void)tapped:(UITapGestureRecognizer *)sender {
NSLog(#"Pressed");
}
I have a UIView and several image Views as subview views on UIView. I need to implement this case, "When a image view is touched on the view then other image view touch event will not delivered".
I use the exclusive touch property to the UIView, but when I touch one of the subviews, I touched at the same time, the touch event of the other subviews also deliver the touch event.
I also set multi touch disable for all the views.
for (UITouch *touch in touches)
{
currentTouch=touch;
if (CGRectContainsPoint([self.view frame], [touch locationInView:self.image1view]))
{
Give desired action here….
[self transformSpinnerwithTouches:touch];
}
else
if (GRectContainsPoint([self.view frame], [touch locationInView:self.imageview2]))
{
Give desired action here as well….
[self dispatchTouchEvent:[touch view]WithTouch:touch];
}
}