我在无限滚动视图中有5张图片。
因此，为了使scrollView无限/圆形，我将我的图像定位为：
5 1 2 3 4 5 1 含义：最后一张图片第一张图片第二张图片.....最后一张图片第一张图片
为了使它变得无限，我有以下代码：
- (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];
}
}
这意味着当我在最后一张照片时，contentOffset的{{1}}被设置为转到第一张照片 - 这样我获得了无限scrollView
scrollView.这条神奇的界限：
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];
}
使用动画自动执行scoll。
除此之外，一切都很棒：
在我查看最后一张图片后，我应该设置滚动视图的偏移量，以便回到带有动画的第一张图片。
好吧，如果我这样做：
[UIView animateWithDuration:1
delay:0
options:UIViewAnimationOptionCurveEaseInOut
animations:^{ self.scrollView.contentOffset = CGPointMake(h, 0); }
completion:NULL];
在观看最后一张照片后，为了到达第一张照片......它会遍历所有其他照片。
我想要的是：在我查看最后一张照片后，让我回到应该使用动画加载到屏幕上的第一张照片，但没有查看它们之间的所有其他照片。谢谢
答案 0 :(得分：4)
如果我看到这个问题，问题是，你再次使用动画将视图滚动回零位置。我相信你需要修改你发布的最后一段代码：
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"
}
而不是你在做什么尝试使用滚动视图，当时只显示3到5个图像（如果它们是全屏的）。如果您的应用程序中有许多图像，它会因为高内存消耗而崩溃。尝试使用这个几乎符合您要求的测试示例：
HEADER：
#import <Foundation/Foundation.h>
@interface IScrollView : UIScrollView <UIScrollViewDelegate> {
NSMutableArray *imagePaths;
UIImageView *imageViews[3];
NSInteger currentImage;
NSTimer *animationTimer;//weak link
}
@end
消息来源：
#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