I have an iOS (4.0) app that I would like to change the alpha of a specific UILabel of just by taping anywhere on the screen. I don't have my interface done programmatically, I just used the interface builder to place the labels for things on the screen.
How can I use a tap gesture to change the alpha of a specific UILabel in my program?
Thanks in advance!
In viewDidLoad:
UITapGestureRecognizer *oneTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapAction:)];
[oneTap setNumberOfTapsRequired:1];
[oneTap setNumberOfTouchesRequired:1];
[self.view oneTap];
Then define the method:
-(void)tapAction:(UIGestureRecognizer *)gesture
{
[self.yourLabel setAlpha:0.5f]; // set the alpha to whatever you want, or animate the fade, whatever
}
-(IBAction)myPressedButton:(id)sender {
float x;
x = theLabel.alpha;
foat a=0.1;
self.theLabel.alpha = x-a;
}
Related
For the past four hours, I have tried many Stack Overlow solutions but none have helped solve my problem.
Here it is,
I have a UIScrollView
Within that ScrollView there is one custom UILabel and 8 custom UIImageViews
I want to detect a long press
Something like this works
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(longPressDidFire:)];
longPress.minimumPressDuration = 0.5;
[scroll addGestureRecognizer:longPress]; //scroll defined elsewhere
However, if I replace the scroll with any subviews of scroll, the long press event never fires.
How do I detect a long press of a subview of a scroll view?
This is quite a messy hack, however, since I can detect long presses of a scroll view, is there any way where I can detect the
position of the press so that I can see which specific subview is
being pressed.
Also, (insert subview here).userInteractionEnabled = YES, I set this property for all my subviews of the scroll view, so this should not be a problem.
I have also tried using touchesBegan and touchesEnded method as suggested elsewhere in Stack Overflow.
Also, for the image views, I do set a new UILongPressGestureRecognizer for every custom image view, using a for loop, as I am aware of the 1 view per gesture recognizer rule.
From A First Time iOS Developer,
Graham
P.S. I'd really prefer if I could find a solution for 1. rather than the messy 2.
More Code As Requested:
In the Init of the view Controller
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(longPressDidFire:)];
longPress.minimumPressDuration = 0.5;
[self.titleLabel addGestureRecognizer:longPress]; //titleLabel property initialized elsewhere
[mainView addSubview:self.titleLabel];
In a "load images" method
for (NSData * dataImg in results) {
//Does some work turning data into an image, into an image view called img
img.delegate = self;
img.userInteractionEnabled = YES;
UILongPressGestureRecognizer *aLongPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(longPressDidFire:)];
aLongPress.minimumPressDuration = 0.5;
[img addGestureRecognizer:aLongPress];
[imgContainer addSubview:img];
}
Even More Code + Notes
self.view (UIView)
->scroll (UIScrollView)
->->mainView (UIView)
->->->titleLabel (UILabel)
->->->imgContainer (UIView)
->->->->images (UIImageViews)
[self.view addSubview:scroll];
[scroll addSubview:mainView];
[mainView addSubview:self.titleLabel];
[mainView addSubview:imgContainer];
[imgContainer addSubview:img]; //done 8x via for loop
Thanks to #RegularExpression's answer, I now am aware that the mainView is getting pressed, but not its subviews, so I need to find a way to display the mainView's subviews above it. :)
Another update, titleLabel works. ImageViews still don't work though. :(
I know this is a bit late and an answer has been chosen, but in case someone else wants a nice simple solution if you've got iOS7.
Inside your delegate of the UILongPressGestureRecognizer implement the gestureRecognizer:shouldRequireFailureOfGestureRecognizer:otherGestureRecognizer selector
Check if otherGestureRecognizer is a UIPanGestureRecognizer and return YES, otherwise return NO
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
if ([otherGestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {
return YES;
}
return NO;
}
The scroll view will actually produce a UIScrollViewPanGestureRecognizer, which is part of the private API, but it's a subclass of UIPanGestureRecognizer so the above works fine.
To support iOS6 or below, then you'll need to loop through the gestureRecognizers of the UIScrollView, detect which one is a UIPanGestureRecognizer and perform the requireGestureRecognizerToFail selector on your UILongPressGestureRecogizer with that.
your code seems to be fine,it should work i think.i used below code and its working fine for me.
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(handleLongPress:)];
longPress.delegate = (id)self;
longPress.minimumPressDuration=0.05;
imageView.userInteractionEnabled = YES;
[imageView addGestureRecognizer:longPress];
and its method,
- (IBAction)handleLongPress:(UILongPressGestureRecognizer *)sender {
NSLog(#"detected");
if (sender.state == UIGestureRecognizerStateEnded){
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:#"Alert" message:#"YES" delegate:nil cancelButtonTitle:#"OK" otherButtonTitles: nil];
[alert show];
}
}
Here i took imageView as subview of scrollview as u said
Since your UIScrollView is the common parent, that's probably where your gesture recognizer needs to be. You can determine which subview is being pressed by looking at the location of the point supplied in your action. So, the individual subviews do not need gesture recognizers.
So, you would do something like this:
- (void)longPressDidFire:(UILongPressGestureRecognizer *)sender
{
if (sender.state == UIGestureRecognizerStateEnded)
CGPoint point = [sender locationInView:scroll];
UIView *tappedView = [scroll hitTest:point withEvent:nil];
So, then you have the view that was long-pressed.
Other things that could cause the action not to fire would be a delegate problem or if the scroll is contained by another view that is intercepting the touch.
HTH
Instead of
[scroll addGestureRecognizer:longPress];
Add the gesture on your subviews, right after you declare them and before you add them to scrollview
[subview addGestureRecognizer:longPress];
Woohoo it works!
The problem was:
imgContainer was a UIView with an empty frame with several UIImageViews as subviews
I was under the impression that as I added a subview to imgContainer, imgContainer would expand.
This is not true.
I had to set imgContainer's frame to the same content frame as the scroll view and then everything became ok.
I hope this answer helps any other future iOS firs timers like me.
I want to create hyperlink like in html text. Is it possible to hyperlink a label in Xcode?
I suggest using the Round Rect Button then setting the background image to be an image that is the same color as your view's background.
Just add a tapGestureRecognizer to that label
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(labelTapped:)];
tapGesture.numberOfTapsRequired = 1;
self.theLabel.userInteractionEnabled = YES;//Since by default, UILabel is not interaction enabled
[self.theLabel addGestureRecognizer:tapGesture];
//Some where in the code
-(void)labelTapped:(UIGestureRecognizer *)sender
{
//Do some stuff
}
In my app i have an UISlider on the scrollView,
I need to move the slider to the next ciel/flor/round value when user removes finger from the slider,
I implemented Touch delegate methods, begin & Cancel but these are not working on slider (may be due to the UIScroll view).
Touch on uiscroll view NOT Working
What to do?
considering your situation i suggest to use UITapGestureRecognizer.
First set up the TapGestureRecognizer on init.
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapRecognizer:)];
[scrollView addGestureRecognizer:tap];
And then get the touches from following:
- (void)tapRecognizer:(UITapGestureRecognizer *)gesture
{
CGPoint touchPoint=[gesture locationInView:scrollView];
}
I've added a TapGestureRecognizer to my self.view:
tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(singleTap:)];
tap.numberOfTapsRequired = 1;
tap.numberOfTouchesRequired = 1;
[self.view addGestureRecognizer:tap];
[tap release];
The view contains a single UIScrollView with images and labels. I want to detect if the user taps on a label or not.
- (void)singleTap:(UIGestureRecognizer*)gestureRecognizer {
CGPoint pt = [gestureRecognizer locationInView:self.view];
UIView *v = [self.view hitTest:pt withEvent:nil];
if ([v isKindOfClass:[UILabel class]]) {
NSLog(#"label!");
return;
}
// else do other stuff if its not a label
However I don't see the label! in my log.
I think it's because userInteractionEnabled is by default NO on UILabels. Try turning that on.
EDIT: It was really a guess, but just to confirm, Apple docs on [UIView hitTest:withEvent:] state:
This method ignores view objects that are hidden, that have disabled user interaction, or have an alpha level less than 0.01.
Your subviews, such as the labels themself, actually hide the user interactions from the underlying view.
Why don't you add the gesture recognizers to your label(s).
Alternatively you may want to use UIButton for the labels.
Or -
if you do not want to determine which label has been touched, you may want to add an invisible view (an empty view, neither a hidden one nor one with alpha=0) on top of all labels and add the gesture recognizers to those.
I have an UIButton and I want to move that button by touching and swiping it in the screen. When I release the touch it will be in the current position. Explain clearly, please.
You can move a view by using touch moved event. There is a sample tutorial MoveMe by Apple which drags a view and after releasing the touch animate the view. Check specially the touch events (touchesBegan, touchesMoved, touchesEnded) in MoveMeView.m to get the idea how they have moved placardView. You can move your button just like the placardView.
Taken from 'drag' move a uibutton so it acts like uiScrollView
check this
you should make move frame from the points and move frame accordingly so that your button moves in places of touches
If you are scripting for iOS 3.2 and above, consider using UIPanGestureRecognizer.
Simply attach an instance of it like this,
...
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePan:)];
panGesture.maximumNumberOfTouches = 1;
panGesture.minimumNumberOfTouches = 1;
[self.button addGestureRecognizer:panGesture];
[panGesture release];
...
and define handlePan: like this,
- (void)handlePan:(UIPanGestureRecognizer *)panGesture {
CGRect buttonFrame = self.button.frame;
CGPoint translation = [panGesture translationInView:panGesture.view];
buttonFrame.origin.x += translation.x;
buttonFrame.origin.y += translation.y;
[panGesture setTranslation:CGPointMake(0, 0) inView:panGesture.view];
self.button.frame = buttonFrame;
}