I want to have UITapGestureRecognizer in a view and touchesBegan in its childview, but the problem is when UITapGestureRecognizer is recognized touchesBegan is not called.
Is it doing this is fine? Or should I need to take another approach ?
Edit : Solved. Setting cancelsTouchesInView property of UITapGestureRecognizerdid the trick for me. By default it is false, so touchesBegan isn't called.
Please find out where are you wrong,
This is a step by step guide on how to implement gesture recognizers in your class:
Conform your class to UIGestureRecognizerDelegate protocol.
Instantiate the gesture recognizer. For example, to instantiate a UITapGestureRecognizer, we will do:
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTapFrom:)];
Here, action is the selector which will handle the gesture. Here, our selector handleTapFrom will look something like:
- (void) handleTapFrom: (UITapGestureRecognizer *)recognizer
{
//Code to handle the gesture
}
The argument to the selector is the gesture recognizer. We can use this gesture recognizer to access its properties, for example, we can find the state of the gesture recognizer, like, UIGestureRecognizerStateBegan, UIGestureRecognizerStateEnded, etc.
Set the desired properties on the instantiated gesture recognizer. For example, for a UITapGestureRecognizer, we can set the properties numberOfTapsRequired, and numberOfTouchesRequired.
Add the gesture recognizer to the view you want to detect gestures for. In our sample code (I will be sharing that code for your reference), we will add gesture recognizers to an imageView with the following line of code:
[self.imageView addGestureRecognizer:tapGestureRecognizer];
After adding the gesture recognizer to the view, set the delegate for the gesture recognizer, i.e. the class which will handle all the gesture recognizer stuff. In our sample code, it would be like:
tapGestureRecognizer.delegate = self;
Note: Assign the delegate after adding the gesture recognizer to the view. Otherwise, the action method won’t be called.
Related
I have a longpress gesture recognizer that I create in ViewDidLoad then attach to a button like this, the button is created in the storyboard and linked to my class.
UILongPressGestureRecognizer *hold = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(secretChange:)];
hold.minimumPressDuration = 5.0;
hold.delegate = self;
[_button addGestureRecognizer:hold];
The class conforms to the GestureRecognizer protocol and I have my selector here
- (void)secretChange:(UILongPressGestureRecognizer *)sender {
// Some stuff
NSLog(#"Secret");
}
The selector is not being called and I cannot figure out why, this seems to be the code everyone gives out on the internet, I have tried removing the minimum duration to make sure I didn't accidentally set it ridiculously long
UPDATE: I am actually adding this gesture recognizer to multiple buttons like this
[_button1 addGestureRecognizer:hold];
[_button2 addGestureRecognizer:hold];
[_button3 addGestureRecognizer:hold];
What is happening is the gesture recognizer is only being applied to the last button I add it to. How do I get the gesture recognizer added to ALL the buttons? Do I need to make a new one for every button?
You should have three instance of UILongPressGestureRecognizer.
Before add a gesture recognizer to a new view, the addGestureRecognizer method will remove the gesture recognizer from the view it has been attached to.
Is there any way to get UITapGestureRecognizer to run on touch began?
I can't use touchesBegan because I am using a UITableView and the super view steals the event essentially.
I just want to detect when the screen is first touched. Why is this so difficult? Maybe I need a different solution than using tapgesturerecognizer?
You can use state property of UIGestureRecognizer to identify various states of any gesture -
#property(nonatomic,readonly) UIGestureRecognizerState state; // the current state of the gesture recognizer
So when the gesture begin, use something like this in your registered handler method -
if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
// Do your stuff
}
You can add a tap gesture recognizer to the tableView in viewDidLoad like this:
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapGestureRecognized:)];
[self.tableView addGestureRecognizer:tapGestureRecognizer];
Then implement this method:
- (void)tapGestureRecognized:(UITapGestureRecognizer *)tapGestureRecognizer {
NSLog(#"tap gesture recognized");
}
Just tested this out, and works fine. For every tap i get the log message on my console. Note that this prevents the tableview from receiving the taps, other gestures will just be handled by the table view as usual.
You need to set delaysContentTouches = NO
Newbie question.
In IB I added UIImageView to scene and set few gestures for it in -viewDidLoad this way:
image.userInteractionEnabled = YES;
image.multipleTouchEnabled = YES;
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(controlPan:)];
[image addGestureRecognizer:pan];
pan.delegate = self;
// and few others gestures same way
...
and gestures worked fine. After that in IB I added UIView to the same scene and implement gestures absolutely identically to previous code, again in -viewDidLoad. But after that gestures stop working for both UIView and UIImageView. Do I need to make .h and .m for this view and to implement gesture recognizers there, or reason can be in something else?
If you have same handler method you need to make distinction from which object gesture came, so you can properly handle action. If you set different handler methods for every object you dont have to care from which object gesture was invoked.
I am overriding my horizontal image UIScrollView with a panning gesture recognizer to detect a user swipe.
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(panGestureCaptured)];
[imgHorizontalScrollView addGestureRecognizer:panGesture];
My question is: Is there a way for me to reset imgHorizontalScrollView's pan gesture recognizer back to default in the panGestureCaptured method? The reason I ask is because since I am overriding this gesture, once the user swipes and the gesture is picked up, I am no longer able to scroll in the scroll view. I also tried to remove the gesture but that also prevents me from being able to scroll.
try UIGestureRecognizerDelegate gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer: with scrollView's gestureRecognizer got by panGestureRecognizer
Try setting
panGesture.cancelsTouchesInView = NO;
If that doesn't work, you should find a way to change your gesture handler to the scrollViewDidScroll: delegate method
I'd like to code my own tap gesture recognizer, to detect the number of taps and number of touches (I don't want to use the iOS tap gesture recognizer because I want to extend it later in various other manners) ;
I tried the following : use the first motionBegin number of touches as the numberOfTouches of the tap, increment the numberOfTaps, and start the tap detection timer to detect the tap gesture if no new taps has been seen in a while
The problem is that one quickly realises that when doing a double-touch tap gesture, iOS either correctly detects one motionBegin with a double touch, or two quick one touch events. I guess a correct implementation should try to detect those quick one touch events that happen closely, but I'm wondering if there is a better way to implement the gesture recognizer.
Someone knows how the iOS tap gesture is implemented?
1. Add UIGestureRecognizerDelegate in your .h file. like
#interface finalScreenViewController : UIViewController <UIGestureRecognizerDelegate>
{
// do your stuff
}
2. Create a view in your viewDidLoad method (or any other method) you wanna to add the gesture in your .m file
ex
UIView * myView=[[UIView alloc]init];
myView.frame=CGRectMake(0,0.self.view.frame.size.width,self.view.frame.size.height);
[self.view addSubView: myView];
UITapGestureRecognizer *letterTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapMethod:)];
letterTapRecognizer.numberOfTapsRequired = 1;
[myView addGestureRecognizer:letterTapRecognizer];
3. you can get view by
- (void) tapMethod:(UITapGestureRecognizer*)sender {
UIView *view = sender.view;
NSLog(#"%d", view.tag);//By tag, you can find out where you had tapped.
}