I have added a gesture recognizer because I want to get the x coordinate of a touch (working on an audio trimmer, so I need the x coordinate for the handles of the trimmer).
I have
UIGestureRecognizer *recognizer;
CGPoint leftControlPoint = [recognizer locationInView:self.view];
NSLog(#"this is where the touch is %#", NSStringFromCGPoint(leftControlPoint));
However, the NSLog simply gives me {0,0}.
Any idea what's going on?
Thanks what I can do?
The proper way to wire up a gesture recognizer is something like this:
// In some method, probably -viewDidLoad:
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self
action:#selector(didTapView:)];
[self.view addGestureRecognizer:tap];
Then:
- (void)didTapView:(UITapGestureRecognizer *)sender {
CGPoint leftControlPoint = [sender locationInView:self.view];
NSLog(#"this is where the touch is %#", NSStringFromCGPoint(leftControlPoint));
}
Related
I am using UIPanGestureRecognizer to slide/scroll a UIView. The following code works well and I am able to slide/scroll the panView. My question is when I end the gesture I should make the panView(UIView) scroll smoothly smiler like UITableView or UIScrollView scroll. So please help me out what should I code in UIGestureRecognizerStateEnded state. Please refer the below code. Thanks in advance!!
UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(scrollpanView:)];
[panRecognizer setDelegate:self];
[panView addGestureRecognizer:panRecognizer];
-(void)scrollpanView:(id)sender{
UIPanGestureRecognizer *gesture = (UIPanGestureRecognizer *)sender;
CGPoint translatedPoint = [gesture locationInView:[panView superview]].x;
if (UIGestureRecognizerStateBegan){
panXAxis = [gesture locationInView:[panView superview]].x;
translatedPoint = CGPointMake(panXAxis+translatedPoint.x, 50);
[panView setCenter:translatedPoint];
}
if ( UIGestureRecognizerStateChanged){
translatedPoint = CGPointMake(panXAxis+translatedPoint.x, 50);
[panView setCenter:translatedPoint];
}
if (UIGestureRecognizerStateEnded){
CGPoint velocity = [gesture velocityInView:[panView superview]]
// How should I scroll smoothly using the 'velocity' value
}
}
I'm trying to make a vertical line from the top of my main view to the bottom, and it will trigger an action when someone swipes and crosses this line from either direction. I've already tried creating a tall thin label and putting a swipe recognizer inside of this, but it does not work the way I want. It only detects a swipe when you start inside of the label and swipe but not if you start outside the label and cross through it.
Here is my code so far,
UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(doSomething)];
swipe.direction = UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionRight;
swipe.numberOfTouchesRequired = 1;
[self.myLabel setUserInteractionEnabled:YES];
[self.myLabel addGestureRecognizer:swipe];
The easiest way is to use the touchesBegan: and touchesMoved: method on a UIView to decide if it's crossed the midway line. You would then just add a view (your line) on top of this view, and you may want to disable user interaction on your "line" view. BTW, a quick dirty way to create a line is to create a view that's 2px wide (or whatever width you want) and set it's background color to your "line" color...
You need to decide in touchesBegan: which side they started on, and then do something like this in touchesMoved::
- (void) touchesMoved: (NSSet *)touches withEvent:(UIEvent *)event {
CGPoint tappedPt = [[touches anyObject] locationInView: self];
if (tappedPt.x > self.frame.width/2 && self.userStartedOnLeftSide)
// User crossed the line...
else if (tappedPt.x < self.frame.width/2 && !self.userStartedOnLeftSide)
// User crossed the line...
else
// You probably don't need this else, the user DID NOT cross the line...
}
Similarly, you could do this in a UIViewController with a swipe gesture recognizer something like this:
- (void)swipe:(UISwipeGestureRecognizer *)recognizer{
CGPoint point = [recognizer locationInView:[recognizer view]];
if (recognizer.state == UIGestureRecognizerStateBegan)
// The user began their swipe at point
else if (recognizer.state == UIGestureRecognizerStateEnded)
// The user ended their swipe at point
// Add some logic to decide if they crossed the line...
}
If you're just trying to detect left and right swipes, you can put it on your main view like so:
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
UISwipeGestureRecognizer *swipe;
swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipe:)];
swipe.direction = UISwipeGestureRecognizerDirectionLeft;
[self.view addGestureRecognizer:swipe];
swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipe:)];
swipe.direction = UISwipeGestureRecognizerDirectionRight;
[self.view addGestureRecognizer:swipe];
}
- (void)handleSwipe:(UISwipeGestureRecognizer *)gesture
{
NSLog(#"%d", [gesture numberOfTouches]);
if (gesture.direction == UISwipeGestureRecognizerDirectionLeft)
{
NSLog(#"LEFT");
}
if (gesture.direction == UISwipeGestureRecognizerDirectionRight)
{
NSLog(#"RIGHT");
}
}
If you wanted to really test to see if you crossed the midpoint, you could use aUIPanGestureRecognizer:
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self.view addGestureRecognizer:[[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(handlePan:)]];
}
- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
static CGPoint startLocation;
static BOOL startAtLeft;
CGPoint location = [gesture locationInView:gesture.view];
if (gesture.state == UIGestureRecognizerStateBegan)
{
startLocation = location;
startAtLeft = (location.x < (gesture.view.frame.size.width / 2.0));
}
else if (gesture.state == UIGestureRecognizerStateEnded)
{
BOOL nowAtLeft = (location.x < (gesture.view.frame.size.width / 2.0));
if (startAtLeft != nowAtLeft)
{
if (startAtLeft)
NSLog(#"swiped across midpoint, left to right");
else
NSLog(#"swiped across midpoint, right to left");
}
}
}
With the pan gesture, you can customize this to your heart's content (e.g. recognize gesture as soon as the user's finger crosses rather than waiting for them to end the gesture, etc.).
I have tried so many thing to get touch inside a UIScrollView but I'm not getting how to do it.
Actually I want to touch inside a UIScrollView and get the location of subview (which i have touched).
You can do it with gesture recognizers. For detect single tap location use UITapGestureRecognizer
UITapGestureRecognizer *tapRecognizer = [[[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tapAction:)] autorelease];
[myScrollView addGestureRecognizer:tapRecognizer];
- (void)tapAction:(UITapGestureRecognizer*)sender{
CGPoint tapPoint = [sender locationInView:myScrollView];
CGPoint tapPointInView = [myScrollView convertPoint:tapPoint toView:self.view];
}
To convert that tapPoint to self.view you can use convertPoint:toView: method in UIView class
Something strange I encountered today while attaching same gesture recogniser to multiple image views. It gets attached to only the last one, in other words, it can be attached to only one view!
I had to create multiple gesture recognisers to meet my requirements.
Following is what I have done. Am I doing correct? Is that's the only way to attach recognisers to the multiple imageviews?
Please note that I don't want to use UITableView or UIVIew and put all imageviews in it and attach gesture recogniser to only UITableView or UIVIew. I have all image scattered and I have to detect which image is being dragged. Thanks.
[imgView1 setUserInteractionEnabled:YES];
[imgView1 setMultipleTouchEnabled:YES];
[imgView2 setUserInteractionEnabled:YES];
[imgView2 setMultipleTouchEnabled:YES];
[imgView3 setUserInteractionEnabled:YES];
[imgView3 setMultipleTouchEnabled:YES];
[imgView4 setUserInteractionEnabled:YES];
[imgView4 setMultipleTouchEnabled:YES];
[imgView5 setUserInteractionEnabled:YES];
[imgView5 setMultipleTouchEnabled:YES];
[imgView6 setUserInteractionEnabled:YES];
[imgView6 setMultipleTouchEnabled:YES];
//Attach gesture recognizer to each imagviews
gestureRecognizer1 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
gestureRecognizer1.delegate = self;
gestureRecognizer2 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
gestureRecognizer2.delegate = self;
gestureRecognizer3 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
gestureRecognizer3.delegate = self;
gestureRecognizer4 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
gestureRecognizer4.delegate = self;
gestureRecognizer5 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
gestureRecognizer5.delegate = self;
gestureRecognizer6 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
gestureRecognizer6.delegate = self;
[imgView1 addGestureRecognizer:gestureRecognizer1];
[imgView2 addGestureRecognizer:gestureRecognizer2];
[imgView3 addGestureRecognizer:gestureRecognizer3];
[imgView4 addGestureRecognizer:gestureRecognizer4];
[imgView5 addGestureRecognizer:gestureRecognizer5];
[imgView6 addGestureRecognizer:gestureRecognizer6];
Yes, one view per gesture recognizer. So if you want only one recognizer, put it on the superview, e.g.:
UILongPressGestureRecognizer *gestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(gestureHandler:)];
[self.view addGestureRecognizer:gestureRecognizer];
And then, in your handler, you can:
- (void)handleLongPress:(UILongPressGestureRecognizer *)sender
{
CGPoint location = [sender locationInView:self.view];
if (sender.state == UIGestureRecognizerStateBegan)
{
for (UIView *view in self.view.subviews)
{
if ([view isKindOfClass:[UIImageView class]] && CGRectContainsPoint(view.frame, location))
{
UIImageView *image = (UIImageView *) view;
// ok, now you know which image you received your long press for
// do whatever you wanted on it at this point
return;
}
}
}
}
By the way, if you do that, you don't need to worry about enabling user interaction on the images, either.
Finally, you don't need to worry about specifying your gesture recognizer's delegate unless you're going to conform to UIGestureRecognizerDelegate, which this isn't. Also note that I'm using a local var for my recognizer because there's no reason to hang onto it.
Update:
While the above code works fine, perhaps even better would be a custom long press gesture recognizer that would fail if the long press didn't take place over an image (this way it's more likely to play well in case you have other gesture recognizers taking place in your view). So:
#import <UIKit/UIGestureRecognizerSubclass.h>
#interface ImageLongPressGestureRecognizer : UILongPressGestureRecognizer
#property (nonatomic, weak) UIImageView *imageview;
#end
#implementation ImageLongPressGestureRecognizer
#synthesize imageview = _imageview;
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
self.imageview = nil;
[super touchesBegan:touches withEvent:event];
CGPoint location = [self locationInView:self.view];
for (UIView *view in self.view.subviews)
{
if ([view isKindOfClass:[UIImageView class]] && CGRectContainsPoint(view.frame, location))
{
self.imageview = (UIImageView *)view;
return;
}
}
self.state = UIGestureRecognizerStateFailed;
}
#end
then create your gesture recognizer accordingly, using this new subclass:
ImageLongPressGestureRecognizer *gestureRecognizer = [[ImageLongPressGestureRecognizer alloc] initWithTarget:self action:#selector(handleLongPress:)];
[self.view addGestureRecognizer:gestureRecognizer];
and then, as a nice little benefit of this subclassing, your main gesture recognizer is simplified, namely:
- (void)handleLongPress:(ImageLongPressGestureRecognizer *)sender
{
if (sender.state == UIGestureRecognizerStateBegan)
{
// you can now do whatever you want with sender.imageview, e.g. this makes it blink for you:
[UIView animateWithDuration:0.5
animations:^{
sender.imageview.alpha = 0.0;
} completion:^(BOOL finished){
[UIView animateWithDuration:0.5
animations:^{
sender.imageview.alpha = 1.0;
}
completion:nil];
}];
}
}
You can't attach a gesture recognizer to more than one object (as you discovered). One solution to what you are doing might be to subclass UIImageView and have setup code in that class so each view creates its recognizer, etc.
I guess, first of all, you should make an array of views and array of recognizers (mutable array, if needed) and then populate it. It will help you to use cycles to avoid code duplication.
As for multiple view with one recognizer - no, it's not possible, answered here.
I want to add simple swipe gesture recognition to my view based iPhone project. Gestures in all directions (right, down, left, up) should be recognized.
It is stated in the docs for UISwipeGestureRecognizer:
You may specify multiple directions by specifying multiple UISwipeGestureRecognizerDirection constants using bitwise-OR operands. The default direction is UISwipeGestureRecognizerDirectionRight.
However for me it doesn't work. When all four directions are OR'ed only left and right swipes are recognized.
- (void)viewDidLoad {
UISwipeGestureRecognizer *recognizer;
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipeFrom:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionRight | UISwipeGestureRecognizerDirectionDown | UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionUp)];
[[self view] addGestureRecognizer:recognizer];
[recognizer release];
[super viewDidLoad];
}
-(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {
NSLog(#"Swipe received.");
}
I fixed this with adding four recognizers to the view but I'm curious to know why didn't it work as advertised in docs?
- (void)viewDidLoad {
UISwipeGestureRecognizer *recognizer;
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipeFrom:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
[[self view] addGestureRecognizer:recognizer];
[recognizer release];
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipeFrom:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionUp)];
[[self view] addGestureRecognizer:recognizer];
[recognizer release];
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipeFrom:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionDown)];
[[self view] addGestureRecognizer:recognizer];
[recognizer release];
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipeFrom:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
[[self view] addGestureRecognizer:recognizer];
[recognizer release];
[super viewDidLoad];
}
-(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {
NSLog(#"Swipe received.");
}
Seems like there is a bug. You can specify the allowed direction(s) as you did. But when you try to access the actual direction that triggered the swipe in the action selector method you still get the bit mask you originally set (for the allowed directions).
This means that checks for the actual direction will always fail when more than 1 direction is allowed.
You can see it for yourself quite easily when you output the value of 'direction' in the selector method (ie -(void)scrollViewSwiped:(UISwipeGestureRecognizer *)recognizer).
Filed a bug report (#8276386) to Apple.
[Update] I got an answer from Apple saying that the behavior works as was intended.
So for example in a table view you can swipe left or right in a table view cell to trigger 'delete' (this would have directions of the swipe gesture set to left and right)
This means that the original workaround is the way it's supposed to be used. The direction property can only be used to get the gestures recognized correctly, but not in the method performed on a successful recognition to compare for the actual direction that triggered the recognition.
I noticed that left/right and up/down gestures work together in pairs, so you only need to specify two gesture recognizers. And the docs do seem to be wrong.
Well that sucks, I solved the problem by adding 2 gestures like Lars mentioned and that worked perfectly...
1) Left/Right
2) Up/Down
UISwipeGestureRecognizer *swipeLeftRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleGesture:)];
[swipeLeftRight setDirection:(UISwipeGestureRecognizerDirectionRight | UISwipeGestureRecognizerDirectionLeft )];
[self.view addGestureRecognizer:swipeLeftRight];
UISwipeGestureRecognizer *swipeUpDown = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleGesture:)];
[swipeUpDown setDirection:(UISwipeGestureRecognizerDirectionUp | UISwipeGestureRecognizerDirectionDown )];
[self.view addGestureRecognizer:swipeUpDown];
UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(didSwipe:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
[self.view addGestureRecognizer:recognizer];
[recognizer release];
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(didSwipe:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
[self.view addGestureRecognizer:recognizer];
[recognizer release];
Now this is the didSwipe function
- (void) didSwipe:(UISwipeGestureRecognizer *)recognizer{
if([recognizer direction] == UISwipeGestureRecognizerDirectionLeft){
//Swipe from right to left
//Do your functions here
}else{
//Swipe from left to right
//Do your functions here
}
}
If your using Xcode 4.2 you can add Gesture Recognizers # the storyboard and then link the GUI Gesture Recognizers to IBActions.
You can find the Gesture Recognizers in the Object Library of the Utility Pane (The bottom of the Right pane).
Then its just a matter of Control-dragging to the appropriate action.
If you want it to detect all four directions, you'll need to create four instances, as you did in your work-around.
Here's Why:
The same instance of UISwipeGestureRecognizer that you create is the instance that gets passed to the selector as sender. So if you set it to recognize all four directions, it will return true for sgr.direction == xxx where xxx is any one of the four directions.
Here's an alternative work-around that involves less code (assumes ARC use):
for(int d = UISwipeGestureRecognizerDirectionRight; d <= UISwipeGestureRecognizerDirectionDown; d = d*2) {
UISwipeGestureRecognizer *sgr = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleSwipeFrom:)];
sgr.direction = d;
[self.view addGestureRecognizer:sgr];
}
Swift 2.1
I had to use the following
for var x in [
UISwipeGestureRecognizerDirection.Left,
UISwipeGestureRecognizerDirection.Right,
UISwipeGestureRecognizerDirection.Up,
UISwipeGestureRecognizerDirection.Down
] {
let r = UISwipeGestureRecognizer(target: self, action: "swipe:")
r.direction = x
self.view.addGestureRecognizer(r)
}
Here is a code sample for UISwipeGestureRecognizer usage. Note comments.
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
//add gesture recognizer. The 'direction' property of UISwipeGestureRecognizer only sets the allowable directions. It does not return to the user the direction that was actaully swiped. Must set up separate gesture recognizers to handle the specific directions for which I want an outcome.
UISwipeGestureRecognizer *gestureRight;
UISwipeGestureRecognizer *gestureLeft;
gestureRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipeRight:)];//direction is set by default.
gestureLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipeLeft:)];//need to set direction.
[gestureLeft setDirection:(UISwipeGestureRecognizerDirectionLeft)];
//[gesture setNumberOfTouchesRequired:1];//default is 1
[[self view] addGestureRecognizer:gestureRight];//this gets things rolling.
[[self view] addGestureRecognizer:gestureLeft];//this gets things rolling.
}
swipeRight and swipeLeft are methods that you use to perform specific activities based on left or right swiping. For example:
- (void)swipeRight:(UISwipeGestureRecognizer *)gesture
{
NSLog(#"Right Swipe received.");//Lets you know this method was called by gesture recognizer.
NSLog(#"Direction is: %i", gesture.direction);//Lets you know the numeric value of the gesture direction for confirmation (1=right).
//only interested in gesture if gesture state == changed or ended (From Paul Hegarty # standford U
if ((gesture.state == UIGestureRecognizerStateChanged) ||
(gesture.state == UIGestureRecognizerStateEnded)) {
//do something for a right swipe gesture.
}
}
UISwipeGestureRecognizer *Updown=[[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(handleGestureNext:)];
Updown.delegate=self;
[Updown setDirection:UISwipeGestureRecognizerDirectionDown | UISwipeGestureRecognizerDirectionUp];
[overLayView addGestureRecognizer:Updown];
UISwipeGestureRecognizer *LeftRight=[[UISwipeGestureRecognizer alloc]initWithTarget:self action:#selector(handleGestureNext:)];
LeftRight.delegate=self;
[LeftRight setDirection:UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionRight];
[overLayView addGestureRecognizer:LeftRight];
overLayView.userInteractionEnabled=NO;
-(void)handleGestureNext:(UISwipeGestureRecognizer *)recognizer
{
NSLog(#"Swipe Recevied");
//Left
//Right
//Top
//Bottom
}
hmm, strange, it works perfect for me, I do exactly same thing
think you should try look at
UIGestureRecognizerDelegate method
- (BOOL)gestureRecognizerShouldBegin:(UISwipeGestureRecognizer *)gestureRecognizer {
// also try to look what's wrong with gesture
NSLog(#"should began gesture %#", gestureRecognizer);
return YES;
}
in logs you must see something like:
should began gesture ; target= <(action=actionForUpDownSwipeGestureRecognizer:, target=)>; direction = up,down,left,right>
use this, it should be the bit operation
gesture.direction & UISwipeGestureRecognizerDirectionUp ||
gesture.direction & UISwipeGestureRecognizerDirectionDown
This was driving me crazy. I finally figured out a reliable way to have multiple swipeGestureRecognizers.
It appears there is a bug in iOS if the name of your "action" selector is the same across multiple swipeGestureRecognizers. If you just name them differently, e.g. handleLeftSwipeFrom and handleRightSwipeFrom, everything works.
UISwipeGestureRecognizer *recognizer;
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleLeftSwipeFrom:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
[[self view] addGestureRecognizer:recognizer];
[recognizer release];
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(handleRightSwipeFrom:)];
[recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
[[self view] addGestureRecognizer:recognizer];
[recognizer release];