Help scrolling through a UIScrollView

I am placing array of images in a scrollview.

I need to autoscroll the scrollview. I am using the timer and increasing the position of scrollview.

My code looks like this.

- (void)autoscrollmethod {
    Timer = [NSTi开发者_开发问答mer scheduledTimerWithTimeInterval:7.5 target:self selector:@selector(moveRect) userInfo:nil repeats:YES];
}
- (void)moveRect {
    NSLog(@">>>>>>>> %d",i);
    [gallery scrollRectToVisible:CGRectMake(i,0,100,100) animated:NO]; 
    if (i==(arraycount+1)*100) {
        [gallery scrollRectToVisible:CGRectMake(0,0,100,100) animated:NO];
        i=200;
    }
    else {
        i=i+100;
    }
} 

It working fine,but I have a problem.

I am scrolling the view to position 800, but scrollRectToVisible:CGRectMake is at 600,then scrollview is not getting back to 600 position,and not autoscroll up to 800.

After 800 it will automatically scrolls normally.

How can I fix this?

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Generally speaking, you should use the contentOffset property of the UIScrollView instead of manually using your own increment variable. Contentoffset changes depending on your scrolling and automatically changes itself.