I have a UILabel control in a view. I want to detect touch event occurred when this label touched. I added the following code, which should work whenever touch happens on the view.
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
// This should be called only when the label is touched, not all the time..
[ [UIApplication sharedApplication] openURL:[NSURL URLWithString:#"http://www.mywebsite.com"] ];
}
Whenever that particular label is touched my code should do the process further, not when the touch is happening anywhere in the view. How do i find out the particular label (or) any control is touched under touchesEnded function ?
Could someone guide me on this?
Thank you.
You can do this by performing a hitTest on the label:
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
CGPoint point = [[touches anyObject] locationInView:label];
if([label hitTest:point withEvent:nil]) {
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:#"http://www.mywebsite.com"]];
} else {
[super touchesEnded:touches withEvent:event];
}
}
Related
Touching anywhere on screen the user should go to the next view in iphone application?
How can we implement this?
Sure you can Make use of this method of touches
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
//Get all the touches.
NSSet *allTouches = [event allTouches];
//Number of touches on the screen
if([allTouches count] > 0)
{
//Navigate to next screen here likewise you generally do
}
else
{
}
}
Good Luck!
Read UIResponder Class Reference for more details
For now you can implement the
(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
method in your viewController class and load the otherViewController possibly by pushing over NavigationController.
I want to make a transparent mask-view over the current window, which just tracks touch events and passing them to the visible views below. However if I set userInteractionEnabled=YES to this mask, this blocks the events and won't be passed below.
Is there any way that I can prevent this view from blocking the events, or manually passing the events below?
Thanks,
I just recently did this for one of my apps and it turned out to be quite simple.
Get ready to subclass UIView:
I called my Mask View the catcher view and this is how the protocol looks:
#interface CatcherView : UIView {
UIView *viewBelow;
}
#property(nonatomic,retain)UIView *viewBelow;
#end
Here you are just subclassing UIView AND keeping a reference to the view bellow.
On the implementation you need to fully implement at least 4 methods to pass the touches to the view, or views bellow, this is how the methods look:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Began");
[self.viewBelow touchesBegan:touches withEvent:event];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Moved");
[self.viewBelow touchesMoved:touches withEvent:event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Ended");
[self.viewBelow touchesEnded:touches withEvent:event];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
NSLog(#"Touch Cancelled");
//Not necessary for my app but you just need to forward it to your view bellow.
}
Just remember to set the view or views that are bellow when you create the view; it is also very important to set the background color to clear, so it acts as a mask. THis is how that looks:
CatcherView *catchView=[[CatcherView alloc] initWithFrame:[self.view bounds]];
catchView.backgroundColor=[UIColor clearColor];
catchView.viewBelow=myViewBellow;
[self.view addSubview:catchView];
Hope it helps and comment if you need more info.
UIKit determines the target view for an event by sending -hitTest:withEvent: messages down the responder chain
Once the target has been found, the event is sent up the responder chain until a responder that handles it is found (often the view that was touched, but not always)
Thus, if you override -[NSView hitTest:withEvent:] in a suitably high up view (perhaps by using a custom window!) you can note all incoming events and call super to have them behave as normal.
I wish to drag from one subview to another within my application (and connect them with a line), and so I need to keep track of the current view being touched by the user.
I thought that I could achieve this by simply calling [UITouch view] in the touchesMoved method, but after a quick look at the docs I've found out that [UITouch view] only returns the view in which the initial touch occurred.
Does anyone know how I can detect the view being touched while the drag is in progress?
And my way:
- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
if ([self pointInside:[touch locationInView:self] withEvent:event]) {
[self sendActionsForControlEvents:UIControlEventTouchUpInside];
} else {
[self sendActionsForControlEvents:UIControlEventTouchUpOutside];
}
}
After a bit more research I found the answer.
Originally, I was checking for the view like so:
if([[touch view] isKindOfClass:[MyView* class]])
{
//hurray.
}
But, as explained in my question, the [touch view] returns the view in which the original touch occurred. This can be solved by replacing the code above with the following:
if([[self hitTest:[touch locationInView:self] withEvent:event] isKindOfClass:[MyView class]])
{
//hurrraaay! :)
}
Hope this helps
UIView is subclass of UIResponder. So you can override touches ended/ began methods in your custom class, that inherits from UIView. Than you should add delegate to that class and define protocol for it. In the methods
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
or whatever interactions you need just send appropriate message to object's delegate also passing this object. E.g.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[delegate touchesBeganInView: self withEvent: event];
}
Basically...
I have a UIScrollView subclass which you can add a target and selector too, which get fired if a touch event is detected within the view. I am using the scroll view as an image gallery, and the touch inside the scroll view is used to fade out the HUD components (UItoolBar, etc):
#implementation TouchableScrollView
- (void)addTarget:(id)_target withAction:(SEL)_action
{
target = _target;
action = _action;
shouldRun = NO;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
shouldRun = YES;
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
shouldRun = NO;
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if(shouldRun)
{
shouldRun = NO;
[target performSelector:action];
}
}
#end
I then have another custom UIView added as a subview to this which has the following set (both of which I have played around with):
self.userInteractionEnabled = YES;
self.exclusiveTouch = YES;
and uses the following to trigger an animation:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
The problem is even when the custom UIView detects the touch and responds (by flipping itself over), the UIScrollView selector also gets fired causing everything to fade out.
Please help, I'm totally stuck?!
better to use this in custom ScrollView class
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
if (!self.dragging) {
[self.nextResponder touchesEnded: touches withEvent:event];
}
[super touchesEnded: touches withEvent: event];
self.nextResponder is scrollView subViews. so event other then dragging (scrolling) will be handled by your main viewController . in main View controller inherit touch event method. there u can check for touch event for particular view or image view.
I'm wondering how to track touches anywhere on the iPhone screen and still have UIButtons respond to taps.
I subclassed a UIView, made it full screen and the highest view in the hierarchy, and overrode its pointInside:withEvent method. If I return YES, I'm able to track touches anywhere on the screen but the buttons don't respond (likely because the view is instructed to handle and terminate the touch). If I return NO, the touch passes through the view and the buttons respond, but I'm not able to track touches.
Do I need to subclass UIButton or is this possible through the responder chain? What am I doing wrong?
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event{
return NO;
}
//only works if pointInside:withEvent: returns YES.
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
NSLog(#"began");
[self.nextResponder touchesBegan:touches withEvent:event];
}
//only works if pointInside:withEvent: returns YES.
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
NSLog(#"end");
[self.nextResponder touchesEnded:touches withEvent:event];
}
Rather then having extra view you can subclass your applications main window and track touches (and other events in it)
#interface MyAppWindow : UIWindow
...
#implementation MyAppWindow
- (void)sendEvent:(UIEvent*)event {
[super sendEvent:event];
if (event.type == UIEventTypeTouches){
// Do something here
}
return;
}
Then set your application window type to MyAppWindow (I did that in MainWindow.xib in IB)