I have a UIImageView and I would like to be able to add two methods to it. One for double tapping the top half and the other for double tapping the bottom half of the ImageView.
Currently the code is just an Outlet referencing an the UIImageView:
#IBOutlet weak var postImage: UIImageView!
Could anyone advise me of how to make this happen or at least point me in the correct direction?
Enable user interactions.
self.postImage.userInteractionEnabled = true
Use UITapGestureRecognizer
Detect tap location.
Enjoy.
use UITapGestureRecognizer (obj-c example, for Swift it's basically the same)
UITapGestureRecognizer *gestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapImageView:)];
[self.imageView addGestureRecognizer:gestureRecognizer];
gestureRecognizer.numberOfTapsRequired = 2;
then you can handle tap position inside of the image view
- (void)tapImageView:(UITapGestureRecognizer *)recognizer
{
CGPoint location = [recognizer locationInView:self.imageView];
if ([self.imageView pointInside:location withEvent:nil]) {
// tap is inside view bounds
if (location.y < self.imageView.bounds.height/2) {
// tap in upper half
}
else {
// tap in lower half
}
}
}
There are 2 ways that came to my mind.
Make the image view as the public property of the cell class and add the gesture recogniser to it in the controller class itself.
Or, after creating the cell object, call a method with self as a parameter and add the gesture recogniser in that method whose target will the self object passed.
Related
I have added a pinch gesture recognizer to a scroll view, using it to close a modal view controller. I did it like so:
UIPinchGestureRecognizer *closePinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:#selector(closeGallery)];
[galleryScrollView addGestureRecognizer:closePinch];
Although it is added to a scrollView, I do not actually use it to zoom only to close the view. Therefore, I have no need for the pinch-out gesture as it indicates zooming in.
Is there a way to easily disable the pinch-out portion of the gesture recognizer and leave the pinch-in untouched?
Based on Crazyrems' answer, the following delegate method did exactly what I needed:
- (BOOL)gestureRecognizerShouldBegin:(UIPinchGestureRecognizer *)gestureRecognizer
{
// Negative velocity indicates pinch out
if (gestureRecognizer.velocity < 0) {
return YES; // <- Register touch event
} else {
return NO; // <- Do not register touch event
}
}
You should implement -gestureRecognizerShouldBegin: in your UIGestureRecognizerDelegate
There's a velocity property in the recognizer passed in parameter, so you can check if it's a pinch in or out, and return YES or NO in consequence.
I want the ability to change how the playback controls are presented while using the new AVPlayerViewController in AVKit. Basically, I want to overide the single finger tap gesture to do something else, and replace that gesture with a double finger tap. I am subclassing AVPlayerViewController to add this functionality.
I can add the double finger tap easily by creating a new UITapGestureRecognizer, but doing so with a single tap does nothing, as the playback controls still appear and my custom gesture method is not called. I assume because the AVPlayerViewController has a gesture with priority that is called instead.
I setup the gestures like normal...
// singleFingerTap: will never fire...
UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleFingerTap:)];
singleFingerTap.numberOfTouchesRequired = 1;
singleFingerTap.delegate = self;
[self.view addGestureRecognizer:singleFingerTap];
// doubleFingerTap: will work correctly...
UITapGestureRecognizer *doubleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(doubleFingerTap:)];
doubleFingerTap.numberOfTouchesRequired = 2;
doubleFingerTap.delegate = self;
[self.view addGestureRecognizer:doubleFingerTap];
Any thoughts on how to achieve this without accessing private properties? Is it even permitted? I know I can create my own view controller with an instance of AVPlayer and then create my own playback controls, but I'm hoping I can use the lightweight AVKit player here with a few simple modifications.
I've tried looping through the gestures in AVPlayerViewController's view and removing them, but the gestureRecognizers property was empty. Even if I could do this, I wouldn't know how to add back the gesture to display the playback controls on a double finger tap instead of the single finger tap.
Any suggestions would be much appreciated! Especially whether this is possible/allowed or not. Thanks!
EDIT:
I have found a way to explicitly unblock the player's private gesture that was blocking my own gesture.
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
id firstGesture = gestureRecognizer;
id secondGesture = otherGestureRecognizer;
if ([firstGesture isKindOfClass:[UITapGestureRecognizer class]] && [secondGesture isKindOfClass:[UITapGestureRecognizer class]]) {
UITapGestureRecognizer *tapGesture = firstGesture;
UITapGestureRecognizer *otherTapGesture = secondGesture;
if (tapGesture.numberOfTapsRequired == otherTapGesture.numberOfTapsRequired && tapGesture.numberOfTouches == otherTapGesture.numberOfTouches) {
// Disable the single tap that shows the playback controls...
return YES;
}
}
return NO;
}
This effectively prevents the playback controls from appearing on a tap, and my singleTapGesture: fires as expected. However, I now have the issue of getting the playback controls to appear on a different gesture. Is it possible to reroute the private gesture, or simulate the private gesture programmatically?
Why not just check/modify the target/remove the default gesture recognizers first?
You can access them with the standard UIView's gestureRecognizers.
The gestures recognizers may be buried inside a private subview.
Another solution would be to set userInteractionEnabled to NO and add your gesture recognizers to the superview or to a "overlay" transparent view.
I have a UITableView with a couple of UITableViewCells in it. Because I only have a couple of cells, there is an area of the table view that's not covered by the cells. And I want to do something when the empty area is tapped.
I tried adding a UITapGestureRecognizer on the table view. It detects the tapping on the empty area, but then the cells fail to respond to tapping. I tried adding the tap gesture recognizer on the super view of the table view, but the result is the same.
There must be a way to do this, but I can't quite figure it out yet. Is there any way to achieve what I want to do?
Try this:
initialize and add the UITapGestureRecognizer to your tableView:
UITapGestureRecognizer *gr = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tap:)];
gr.delaysTouchesBegan = YES;
gr.delegate = self;
[_tableView addGestureRecognizer:gr];
implement the gesture recognizer delegate method:
-(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{
CGPoint tapPoint = [gestureRecognizer locationInView:_tableView];
UIView * clickedView = [_tableView hitTest:tapPoint withEvent:nil];
NSString *viewClassName = NSStringFromClass(clickedView.class);
return ![viewClassName hasPrefix:#"UITableViewCell"];
}
this way every tap you do outsude cells (but inside the tableview) will be recognized with your UITapGestureRecognizer
The last line: return ![viewClassName hasPrefix:#"UITableViewCell"];
should be changed to return [viewClassName hasPrefix:#"UITableView"]; since the cell you are clicking doesn't have to be a UITableViewCell, but a UIView or some other custom view
I have a small UITableView that is hidden when the view is loaded. When i click on "SHOW" UIButton, the UITableView is made visible by myTableView.hidden=NO;
I want to hide UITableView when a user touches outside its frame. Thanks for any help!
Best Approach
Simple.Before show up the UITable View add one more grayed out/Transparent view then add tap gesture recogniser on it to hide it . That's it.
Show Overlay View first - alpha will be 0.5f and background color should be clear color.
show the table view.
NOTE: over lay view should have tap recogniser which will hide the overlay and table view
in View did load
UITapGestureRecognizer *tapRecog = [[UITapGestureRecognizer alloc] initWithTarget:self
action:#selector(overlayDidTap:)];
[myOverLayView addGestureRecognizer:tapRecog];
- (void)overlayDidTap:(UITapGestureRecognizer *)gesture
{
//hide both overlay and table view here
}
Bad Approach
We should not add tap recogniser on main view itself. Because it may have lots of
controls inside of it. so when user tap on it. it will perform its operation. So to avoid
it we can simulate the same behaviour by above approach
You can get touch position by this:
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTapGestureCaptured:)];
[self.view addGestureRecognizer:singleTap];
- (void)singleTapGestureCaptured:(UITapGestureRecognizer *)gesture
{
CGPoint touchPoint=[gesture locationInView:self.View];
}
Then just check if the point is in tableview frame. If not then hide the tableview. Hope this help. :)
Subclass UITableView, override pointInside:withEvent:. It is templated for this reason.
Something like:
-(BOOL)pointInside:(CGPoint) point withEvent:(UIEvent*) event
{
BOOL pointIsInsideTableView = [super pointInside:point withEvent:event];
BOOL pointIsOutsideTableView = // Some test
return pointIsInsideTableView || pointIsOutsideTableView;
}
So you can catch the touch in table view implementation, where it belongs logically in this case.
currently I want to let UITextView to have a double tap gesture. It seems UITableView has its own double tap gesture, when we double tapped, some text will be selected. So I want to remove this default double tap gesture to my own gesture recognizer. I tried many methods, and all failed. It seems there's no way to remove the default recognizer of UITextView. I also want to add a transparent view on this UITextView to do double tap event, but this subview will block other gestures on UITextView. Is there some method to add double tap gesture recognizer to UITextView? I really hope there will be a work around.
I am still expecting a work around of iOS5 :)
There are a number of other gesture recognizers attached to a text view. Since you don't seem to need them. You can remove them.
myTextView.gestureRecognizers = nil;
before adding your double tap recognizer. It works.
then you can add
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(mySelector)];
tapRecognizer.numberOfTapsRequired = 2;
tapRecognizer.numberOfTouchesRequired = 1;
[myTextView addGestureRecognizer:tapRecognizer];
I have the solution on iOS6, we can use UIGestureRecognizerDelegate, and override gestureRecognizerShouldBegin: and gestureRecognizer:shouldReceiveTouch:. In this two method, we can check if the gesture is doubleTapGestureForZooming, if not return NO, or return YES. This works perfect in iOS6, but in iOS5 these two delegate method hasn't been called, so iOS5 may need another workaround.
Finally, I get the workaround, we can override the addGestureRecognizer method of UITextView to remove default gesture, wish this will help somebody else.
PS: we really can't remove system gestures of UITextView, we even can't change their property. It seems when event happens, all gestures of UItextview will be added again.
I know this question is old, but to keep it current for future searchers, I figured I would add another solution that has worked for me from iOS 7 through 10. It basically brings together the solutions discussed here and here but tweaks them to get the UITextView to recognize the custom double tap.
It does this by subclassing the UITextView and overriding the addGestureRecognizer: method in order to inject our custom callback into the double-tap gesture and configure the single-tap gesture to respect the new double tap hook.
I do this in addGestureRecognizer: because a UITextView constantly deletes and adds gestures depending on its current state and so you constantly have to reset it back up.
This code should be enough to get someone started:
#interface MyCustomTextView ()
/**
* we want to keep track of the current single-tap gesture so we can make sure
* it waits for a double-tap gesture to fail before firing
*/
#property (weak, nonatomic) UITapGestureRecognizer *singleTap;
/**
* we want to keep track of the current double-tap gesture so we can tell a single
* tap gesture to ignore this double-tap when the single tap gesture changes
*/
#property (weak, nonatomic) UITapGestureRecognizer *doubleTap;
#end
#implementation MyCustomTextView
/**
* this will fire when the text view is double-tapped
*
* #param tgr
*/
- (void)_handleTwoTaps:(UITapGestureRecognizer *)tgr
{
// ADD CODE HERE
}
/**
* the reason why I've overridden this methods is these gestures change quite a bit
* depending on the state of the UITextView, (eg, when in focus and out of focus)
* and so this provides a reliable way to make sure any new gestures get updated
* with custom overrides.
*
* #param gestureRecognizer
*/
- (void)addGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
{
[super addGestureRecognizer:gestureRecognizer];
if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {
UITapGestureRecognizer *tgr = (UITapGestureRecognizer *)gestureRecognizer;
if ([tgr numberOfTapsRequired] == 1 && [tgr numberOfTouchesRequired] == 1) {
self.singleTap = tgr;
if (self.doubleTap) {
[tgr requireGestureRecognizerToFail:self.doubleTap];
}
} else if ([tgr numberOfTapsRequired] == 2 && [tgr numberOfTouchesRequired] == 1) {
[tgr addTarget:self action:#selector(_handleTwoTaps:)];
self.doubleTap = tgr;
if (self.singleTap) {
[self.singleTap requireGestureRecognizerToFail:tgr];
}
}
}
}
// NOTE: I'm not sure if this is needed but it's been there for years
// and so I thought I would include it just in case
- (void)removeGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
{
if ([gestureRecognizer isKindOfClass:[UITapGestureRecognizer class]]) {
UITapGestureRecognizer *tgr = (UITapGestureRecognizer *)gestureRecognizer;
if ([tgr numberOfTapsRequired] == 2 && [tgr numberOfTouchesRequired] == 1) {
[tgr removeTarget:self action:#selector(_handleTwoTaps:)];
}
}
[super removeGestureRecognizer:gestureRecognizer];
}
#end