frame by frame animation with UIGestureRecognizer

Question

I would like to show an animation with images of an object rotating. I have an NSArray with frames of the object and I would like to display them frame by frame with the property of UIImageView animationImages.

The problem is that I would like to control the animation with UISwipeGestureRecognizer (Right and Left). And depending on the speed of the gesture the object should rotate faster or slower. I think is not possible because the gesture it is called just once and not continuously.

(NOTE: this is my first question in StackOverflow)

Thank you in advance

EDIT: I just post my solution. Maybe it can be useful for anybody. I think it's useful.

Firstly: add gesture to the view.

self.recognizer = [[UISwipeGestureRecognizer alloc] init];
self.recognizer.cancelsTouchesInView=NO;
[self.view addGestureRecognizer:self.recognizer];

Secondly: in tocuhMoved method I display the frame that I need depending of the direction of the previous touch. It is called by the event of the user.

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{


    NSInteger image= [self.animationView.animationImages indexOfObject:self.animationView.image];
    UITouch *touch = [touches anyObject];
    NSLog(@"Touch moved with index:%i", image);

    if ((positionTouch.x<[touch locationInView:self.animationView].x)) {
        if (image==24) {
            self.animationView.image=[self.animationView.animationImages objectAtIndex:0];
        }
        else{
            self.animationView.image=[self.animationView.animationImages objectAtIndex:image+1];
        }
    }
    else if((positionTouch.x>[touch locationInView:self.animationView].x)){
        if (image==0) {
            self.animationView.image=[self.animationView.animationImages objectAtIndex:24];
        }
        else{
            self.animationView.image=[self.animationView.animationImages objectAtIndex:image-1];
        }

    }


    positionTouch= [touch locationInView:self.animationView];
}

Don't forget <UIGestureRecognizerDelegate>

with this method, I fill the array of frames...

-(void)addPictures{
    NSMutableArray* mArray=[[NSMutableArray alloc]initWithCapacity:25];
    for (int i=0; i<25; i++) {
        [mArray insertObject:[UIImage imageNamed:[NSString stringWithFormat:@"Picture %i.jpg", i+1]] atIndex:i];
    }

    self.animationView.image=[mArray objectAtIndex:0];
    self.animationView.animationImages=mArray;


    [self.view addSubview:self.animationView];

}

Answer 1

It's actually very simple to control the speed of an animation. In fact, it's so simple (because CALayer conforms to the CAMediaTiming protocol) that the property to control it is literally called speed. It's all a matter of using the gesture as a sort of analog for a slider, and calculating an x value relative to it's location onscreen. This should be a suitable starting point:

//Speed changes necessitate a change in time offset, begin time, and
//speed itself.  Simply assigning to speed it not enough, as the layer needs
//to be informed that it's animation timing function is being mutated.  By
//assigning a new time offset and a new begin time, the layer 
//automatically adjusts the time of any animations being run against it
layer.timeOffset = [layer convertTime:CACurrentMediaTime() fromLayer:nil];
layer.beginTime = CACurrentMediaTime();
layer.speed = ([self.gesture locationInView:self.view].x / CGRectGetWidth(self.view.bounds));