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");
}
Related
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)
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.
Quick question: how do i detect if a tap gesture recognizer is within a subview of the view it is added to? Eg. if i click on an object such as a square that has been added as a subview to a background which a tap gesture recognizer has been added to, how do I detect that it has been tapped?
You can grab the point of the tap off the gesture recognizer when your handler method is called respective to any view you wish using -locationInView:. Then, use the following method on UIView: - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event to get a reference to the actual sub view that was tapped remembering that the point you pass in is in the same coordinate space as the view.
Some code to get you started:
CGPoint point = [tapGestureRecognizer locationInView:parentView];
UIView *tappedView = [parentView hitTest:point withEvent:nil];
For hit testing to work the view needs to have the userInteractionEnabled property set to YES. Many views, such as UILabels have this set to NO by default. So prior to the above:
self.subviewOfInterest.userInteractionEnabled = YES;
maybe you should set as:
subviews.userInteractionEnabled = YES;
good luck!
you can use the requireGestureRecognizerToFail: to recognize the tap on subview please refer this code
I have a UITextField in my iOS app. When a user enters text and clicks Return, the keyboard goes away due to a call to an IBAction with "resignFirstResponder."
However, XCode does not let me drag a line from the UIView itself to File Owner. How do I associate touching the background of a UIView with an IBAction that makes the keyboard go away?
You can use UITapGestureRecognizer. see: Dismiss keyboard by touching background of UITableView
so instead of tableview, just add it to your view instead:
UITapGestureRecognizer *gestureRecognizer = [[[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(hideKeyboard)] autorelease];
gestureRecognizer.cancelsTouchesInView = NO; //so that action such as clear text field button can be pressed
[self.view addGestureRecognizer:gestureRecognizer];
and have a method to hide your keyboard
- (void) hideKeyboard {
[self.view endEditing:YES];
}
You've already noticed that you can't drag from the UIView to the file's owner to assoctiate an action with a touch.
The way to work around this is to change the class of the background view from UIView to UIControl and hook up an action from there to a method in your controller to stop editing.
That's because a UIControl can respond to touch events, and a UIView does not, but a UIControl subclasses UIView, and so it can be used in place of a UIView.
I wrote an example project a while ago that uses this technique. Have a look at the secondViewController's xib file and see how I've change the class of the background view and hooked it up to a an action in the controller to dismiss the keyboard.
Use the touchesBegan with Event and end editing on the view:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[self.view endEditing:YES];
}
One easy way to do it is to create a big transparent UIButton behind the view.