Watchkit: How to loop an image from left to right in objective c?

Question

So I have an image that I want to loop it by its origin x. Say the image is 300px in width. On the 42mm apple watch, it's 156px wide. I want to loop the image so that it look like a runway.

in my NSTimer interval:

UIImage*imgBg = [UIImage imageNamed:@"bgRun.png"];
int x = x-1;
[imgBg drawInRect:CGRectMake(x,0, 156,195)];

[groupBg setBackgroundImage:imgBg];

Few questions:

How to get an UIImage based on the origin x, y or frames in Watch OS? What function should I use? DrawInRect doesn't seem the correct function.

It doesn't seem like UIImageView works on watchkit because it's based on UIView.

Any advice would be grateful. Thank you.

Answer 1

In watchOS 2 you cannot animate objects like it happens under iOS. It means you just can set absolute values for an object position (WKInterfaceObjectHorizontalAlignment) by using a callback in animateWithDuration:animations of WKInterfaceController:

For example infinite animation from the left to the right will be look like this:

- (void) moveLeft {
    [self animateWithDuration:5.0 animations:^{
         [self.animatableObject setHorizontalAlignment:WKInterfaceObjectHorizontalAlignment.Left];
    }];
    [NSTimer scheduledTimerWithTimeInterval:5.0f target:self selector:@selector(moveRight) userInfo:nil repeats:NO];
}

- (void) moveRight {
    [self animateWithDuration:5.0 animations:^{
        [self.animatableObject setHorizontalAlignment:WKInterfaceObjectHorizontalAlignment.Right];
    }];
    [NSTimer scheduledTimerWithTimeInterval:5.0f target:self selector:@selector(moveLeft) userInfo:nil repeats:NO];
}

- (void) startInfiniteAnimation {
    [self moveLeft];
}