iOS:UIScrollView分页无法正常工作 [英] iOS : UIScrollView paging not working properly

问题描述

我正在将AsyncImageView添加到UIScrollView以从Web加载图像，它的工作正常，我添加了8张图像.问题是paging，我已将pagingEnable启用为YES，但是并没有达到我想要的效果，我正在尝试将其设置为contentOffset，并使用不同的x，但不会有任何效果.我希望在滚动或选择next或previous选项时，每个图像都应出现在UIScrollView的center中.

I'm adding AsyncImageView into UIScrollView to load images from web, its working fine, there are 8 images i've added. Problem is of paging I've enabled pagingEnable to YES but it won't come as per I want, I'm trying to setting it contentOffset with different x but it won't any effects. I want that each image should come in center of UIScrollView when I scroll or choose next or previous option.

这是我将图像添加到UIScrollView

arrImgUrls是一个NSArray

arrImgUrls is an NSArray

_currentImage，_imageCount是整数

_currentImage, _imageCount are integers

-(void)setImagesToScrollView
{
    [btnPrev setEnabled:NO];

    _currentImage = 0;

    _imageCount = [arrImgUrls count];

    int x=20;
    int y=0;
    int w=213;
    int h=160;

    for (int i=0; i<[arrImgUrls count]; i++) 
    {
        AsyncImageView *asyncImageView = [[AsyncImageView alloc] initWithFrame:CGRectMake(x, y, w, h)];
        [asyncImageView setDelegate:self];
        [asyncImageView.layer setMasksToBounds:YES];        
        NSString *urlImage = [arrImgUrls objectAtIndex:i];
        NSURL *url = [NSURL URLWithString:urlImage];
        [asyncImageView loadImageFromURL:url];
        [asyncImageView release];
        [scrollImages addSubview:asyncImageView];
        x=(x+w)+10;
    }

    scrollImages.contentSize=CGSizeMake(x, scrollImages.frame.size.height);
}

这是我用来在UIScrollView中显示previous或next图像的代码.

This is code I used to show previous or next images in UIScrollView.

-(IBAction)prevImage:(id)sender
{    
    _currentImage--;

    [btnNext setEnabled:YES];
    
    if (_currentImage<=0)
    {
        _currentImage = 0;
        [btnPrev setEnabled:NO];
    }

    [scrollImages setContentOffset:CGPointMake((_currentImage*imageWidth)+10, 0) animated:NO];
}

-(IBAction)nextImage:(id)sender
{    
    _currentImage++;

    [btnPrev setEnabled:YES];

    if (_imageCount-1 == _currentImage)
    {
        [btnNext setEnabled:NO];
    }

    [scrollImages setContentOffset:CGPointMake(_currentImage*imageWidth, 0) animated:NO];
}

所有加载并添加到UIScrollView的图像的唯一问题是，当用户scrolls或执行previous或next时，在center中显示该图像.

All images loaded and added to UIScrollView only problem is to show it in center when user scrolls or do previous or next.

请指出我做错了什么地方

Please point me where I'm doing wrong?

谢谢！

推荐答案

首先要确保_currentImage是否正确维护?

First of all make sure that _currentImage is maintain properly or not?

现在尝试关注下一张图片

Now try following for next image

CGRect frame;
frame.origin.x = (imageWidth * _currentImage) +10;
frame.origin.y = 0;
frame.size = self.scrollView.frame.size;
[self.scrollView scrollRectToVisible:frame animated:YES]; // NO if you don't want animation

代替此行

[scrollImages setContentOffset:CGPointMake(_currentImage*imageWidth+10, 0) animated:NO];

&对于上一张图片

& for previous image

CGRect frame;
frame.origin.x = (imageWidth * _currentImage) - 10;
frame.origin.y = 0;
frame.size = self.scrollView.frame.size;
[self.scrollView scrollRectToVisible:frame animated:YES]; // NO if you don't want animation

还有一个很好的例子，就像您想要的

and here one nice example just like you want

图像库

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