animation with infinite scrollView - iphone

Question

I have 5 pictures inside an infinite scrollView.
So in order to make that scrollView infinite/circular I positioned my images like this:
5 1 2 3 4 5 1
meaning: last picture first picture second picture.....last picture first picture
And in order for it to become infinite I have the following code:
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
if(self.scrollView.contentOffset.x == 0){
[self.scrollView scrollRectToVisible:CGRectMake(self.view.frame.size.width*pathImages.count, 0, self.view.frame.size.width, self.view.frame.size.height) animated:NO];
}
else if (self.scrollView.contentOffset.x == self.view.frame.size.width*(pathImages.count+1)) {
[self.scrollView scrollRectToVisible:CGRectMake(self.view.frame.size.width,0 ,self.view.frame.size.width, self.view.frame.size.height) animated:NO];
}
}
which means that when I'm at the last picture the contentOffset of the scrollView is set to go to the first picture-in this way I get an infinite scrollView.
What I wanted next was for my scrollView to slide automatically-for this I set a timer which calls one method-onTimer:
- (void) onTimer{
NSLog(#"flip pages");
if(h < pathImages.count*self.view.frame.size.width)
{
h+= self.view.frame.size.width;
}
else
{
h=self.view.frame.size.width;
}
if(self.scrollView.contentOffset.x == 0){
[self.scrollView scrollRectToVisible:CGRectMake(self.view.frame.size.width*pathImages.count, 0, self.view.frame.size.width, self.view.frame.size.height) animated:NO];
}
if (self.scrollView.contentOffset.x == self.view.frame.size.width*pathImages.count)
{
[self.scrollView scrollRectToVisible:CGRectMake(self.view.frame.size.width,0 ,self.view.frame.size.width, self.view.frame.size.height) animated:NO];
}
else
[UIView animateWithDuration:1
delay:0
options:UIViewAnimationOptionCurveEaseInOut
animations:^{ self.scrollView.contentOffset = CGPointMake(h, 0); }
completion:NULL];
}
This magic line:
[UIView animateWithDuration:1
delay:0
options:UIViewAnimationOptionCurveEaseInOut
animations:^{ self.scrollView.contentOffset = CGPointMake(h, 0); }
completion:NULL];
does the scoll automatically with animation.
Everything is great except this:
after I view the last picture I should set the offset of scroll view in order to get back to the first picture with animation.
Well if I do that:
if (self.scrollView.contentOffset.x == self.view.frame.size.width*pathImages.count)
{
[UIView animateWithDuration:1
delay:0
options:UIViewAnimationOptionCurveEaseInOut
animations:^{ [self.scrollView scrollRectToVisible:CGRectMake(self.view.frame.size.width,0 ,self.view.frame.size.width, self.view.frame.size.height) animated:NO]; }
completion:NULL];
}
after the last picture is viewed in order to get to the first picture...it loops through all the other pictures.
What I want is this:after I view the last picture to get me back to the first picture which should be loaded on screen using animation, but without viewing all the other pictures between them.Thanks

Answer 1

If I see this correctly, the problem is, that you again use the animation to scroll the view back to zero position. I believe you need to modify the last bit of code you posted to something like this:
if (self.scrollView.contentOffset.x == self.view.frame.size.width*pathImages.count)
{
[self.scrollView scrollRectToVisible:CGRectMake(self.view.frame.size.width,0 ,self.view.frame.size.width, self.view.frame.size.height) animated:NO];//no animation on returning
[self onTimer];//even if this code is already inside method "onTimer"
}
Rather then what you are doing try using a scrollview that displays only 3 to 5 images at the time (if they are fullscreen). If you will have many images in your application, it will crash because of high memory consumption. Try playing with this test example that does nearly what you want:
HEADER:
#import <Foundation/Foundation.h>
#interface IScrollView : UIScrollView <UIScrollViewDelegate> {
NSMutableArray *imagePaths;
UIImageView *imageViews[3];
NSInteger currentImage;
NSTimer *animationTimer;//weak link
}
#end
SOURCE:
#import "IScrollView.h"
#implementation IScrollView
- (UIImage *)imageFromResourcesWithName:(NSString *)name {
UIImage *ret = [[UIImage alloc] initWithContentsOfFile:[[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:name]];
return [ret autorelease];
}
- (id)initWithFrame:(CGRect)frame {
if((self = [super initWithFrame:frame])) {
imagePaths = [[NSMutableArray alloc] init];
[imagePaths addObject:#"imag1.png"];
[imagePaths addObject:#"imag2.png"];
[imagePaths addObject:#"imag3.png"];
[imagePaths addObject:#"imag4.png"];
[imagePaths addObject:#"imag5.png"];
imageViews[0] = [[UIImageView alloc] initWithFrame:CGRectMake(320.0f*0, .0f, 320.0f, 480.0f)];
imageViews[1] = [[UIImageView alloc] initWithFrame:CGRectMake(320.0f*1, .0f, 320.0f, 480.0f)];
imageViews[2] = [[UIImageView alloc] initWithFrame:CGRectMake(320.0f*2, .0f, 320.0f, 480.0f)];
[self addSubview:imageViews[0]];
[self addSubview:imageViews[1]];
[self addSubview:imageViews[2]];
imageViews[0].image = [self imageFromResourcesWithName:[imagePaths objectAtIndex:0]];
imageViews[1].image = [self imageFromResourcesWithName:[imagePaths objectAtIndex:1]];
imageViews[2].image = [self imageFromResourcesWithName:[imagePaths objectAtIndex:2]];
currentImage = 1;
self.contentOffset = CGPointMake(320.0f*currentImage, .0f);
self.contentSize = CGSizeMake(3.0f*320.0f, 480.0f);
self.delegate = self;
animationTimer = [NSTimer scheduledTimerWithTimeInterval:1.0/60.0 target:self selector:#selector(scrollFragment) userInfo:nil repeats:YES];
}
return self;
}
- (void)repositionIfNeeded {
CGFloat offsetX = self.contentOffset.x;
NSInteger iCount = [imagePaths count];
if(offsetX > 320.0f*1.75f) {
self.contentOffset = CGPointMake(offsetX-320.0f, .0f);
imageViews[0].image = imageViews[1].image;
imageViews[1].image = imageViews[2].image;
NSInteger imageToLoad = currentImage+2;
if(imageToLoad>iCount-1)
imageToLoad -= iCount;
imageViews[2].image = [self imageFromResourcesWithName:[imagePaths objectAtIndex:imageToLoad]];
currentImage++;
if(currentImage>iCount-1)
currentImage -= iCount;
}
else if(offsetX < 320.0f*.25f) {
self.contentOffset = CGPointMake(offsetX+320.0f, .0f);
imageViews[2].image = imageViews[1].image;
imageViews[1].image = imageViews[0].image;
NSInteger imageToLoad = currentImage-2;
if(imageToLoad<0)
imageToLoad += iCount;
imageViews[0].image = [self imageFromResourcesWithName:[imagePaths objectAtIndex:imageToLoad]];
currentImage--;
if(currentImage<0)
currentImage += iCount;
}
}
- (void)scrollFragment {
self.contentOffset = CGPointMake(self.contentOffset.x+1.0, .0f);
[self repositionIfNeeded];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
[self repositionIfNeeded];
}
- (void)dealloc {
[imageViews[0] release];
[imageViews[1] release];
[imageViews[2] release];
[imagePaths release];
}
#end