Iphone 如何实现对uiscroll视图的延迟加载

如何实现对uiscroll视图的延迟加载

我正在从web服务中拍摄15幅图像，并将其添加到UIscrollview 我想在滚动视图中添加临时图像，当图像准备好后，它可以将图像添加到uiscrollview

-(void)loadthscroll:(NSMutableArray *)idarray:(NSMutableArray *)imgarray
{



/*************scroll for scroll in in theater******************/

scrollview_intheater= [[UIScrollView alloc] initWithFrame:CGRectMake(0, btn_thhead.frame.size.height,view_banner.frame.size.width, view_intheater.frame.size.height-btn_thhead.frame.size.height)];
[view_intheater addSubview:scrollview_intheater];

[scrollview_thcsoon removeFromSuperview];
adj=5;
currentx=5;
for(int i=0;i<[imgarray count];i++)

{

    btn_theater_ct = [UIButton buttonWithType:UIButtonTypeCustom];
    btn_theater_ct.frame=CGRectMake(currentx, 5, 95, 120);
    [btn_theater_ct addTarget:self action:@selector(theaterAction:) forControlEvents:UIControlEventTouchDown];
    [scrollview_intheater addSubview:btn_theater_ct];
    addr = [imgarray objectAtIndex:i];
    addr = [addr stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
    //NSLog(@"addr-------%@",addr);
    data_theater = [NSData dataWithContentsOfURL:[NSURL URLWithString:addr ] ];        
    [btn_theater_ct setBackgroundImage:[UIImage imageWithData:data_theater] forState:UIControlStateNormal];
    currentx +=btn_theater_ct.frame.size.width+adj;
    btn_theater_ct.tag=i;
    [scrollview_intheater setContentSize:CGSizeMake(currentx,0)];
    NSLog(@"add th scroll--%d----%d",[imgarray count],i);

}


}

-（void）loadthscroll:（NSMutableArray*）idarray:（NSMutableArray*）imgarray
{
/*************剧院里的滚动******************/
scrollview_-intheter=[[UIScrollView alloc]initWithFrame:CGRectMake（0，btn_-thhead.frame.size.height，view_-banner.frame.size.width，view_-intheter.frame.size.height-btn_-thhead.frame.size.height）]；
[在水中查看添加子视图：在水中滚动查看]；
[scrollview_thcsoon从SuperView中移除]；
adj=5；
电流x=5；
对于（int i=0；i
使用
加载图像设置整个UIScrollView
创建一个交换给定图像的方法，并根据需要更新内容大小
添加一个例程并下载图像
现在，您可以设置UIScrollView并调用例程进行下载。下载完成后，调用方法交换图像，您就完成了。
尝试研究GCD（GrandCentralDispatch）并使用您的场景。
也许这会适合你

    -(void)loadthscroll:(NSMutableArray *)idarray:(NSMutableArray *)imgarray
    {

    scrollview_intheater= [[UIScrollView alloc] initWithFrame:CGRectMake(0, btn_thhead.frame.size.height,view_banner.frame.size.width, view_intheater.frame.size.height-btn_thhead.frame.size.height)];
    [view_intheater addSubview:scrollview_intheater];

    [scrollview_thcsoon removeFromSuperview];
    adj=5;
    currentx=5;


    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
//Here, do your iteration part like parsing URL from array and hitting the service which is background thread.            

            for(int i=0;i<[imgarray count];i++)
          {
                btn_theater_ct = [UIButton buttonWithType:UIButtonTypeCustom];
                btn_theater_ct.frame=CGRectMake(currentx, 5, 95, 120);
                [btn_theater_ct addTarget:self action:@selector(theaterAction:)                                                 forControlEvents:UIControlEventTouchDown];
                [scrollview_intheater addSubview:btn_theater_ct];

            currentx +=btn_theater_ct.frame.size.width+adj;
                [scrollview_intheater setContentSize:CGSizeMake(currentx,0)];

            NSLog(@"add th scroll--%d----%d",[imgarray count],i);
            addr = [imgarray objectAtIndex:i];
                addr = [addr stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
                //NSLog(@"addr-------%@",addr);
                data_theater = [NSData dataWithContentsOfURL:[NSURL URLWithString:addr ] ];   
            UIImage *receivedImage = [UIImage imageWithData:data_theater];
            }
                dispatch_async(dispatch_get_main_queue(), ^{

//Here, do your UI work like set the background image which is include in main thread                    

                    if([receivedImage isKindOfClass:[UIImage class]])
                    {
                        [btn_theater_ct setBackgroundImage: receivedImage];
                    btn_theater_ct.tag=i;
                    }
                });

        });

    }

-（void）loadthscroll:（NSMutableArray*）idarray:（NSMutableArray*）imgarray
{
scrollview_-intheter=[[UIScrollView alloc]initWithFrame:CGRectMake（0，btn_-thhead.frame.size.height，view_-banner.frame.size.width，view_-intheter.frame.size.height-btn_-thhead.frame.size.height）]；
[在水中查看添加子视图：在水中滚动查看]；
[scrollview_thcsoon从SuperView中移除]；
adj=5；
电流x=5；
调度异步（调度获取全局队列（调度队列优先级后台，0）^{
//在这里，执行迭代部分，比如解析数组中的URL并点击作为后台线程的服务。
对于（int i=0；i我在几天前就遇到了同样的问题，但我现在已经解决了
进口

#import "UIImageView+AFNetworking.h"

并实施其方法

- (void)setImageWithURL:(NSURL *)url  placeholderImage:(UIImage *)placeholderImage;

要使用此功能，您必须使用AFNetworking类