2

我正在下载一组图像来创建动画。如何在下载开始时显示活动指示器以及何时完成隐藏活动指示器。

self.img = [[UIImageView alloc] initWithFrame:CGRectMake(0, 65, self.view.frame.size.width, self.view.frame.size.width-70)];



        img.animationImages = [NSArray arrayWithObjects:

                                   [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],

                                   [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],

                                   [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],

                                   [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],




        img.animationDuration = 20.0f;

        img.animationRepeatCount = 0;

        [img startAnimating];

        [self.view addSubview: img];
4

2 回答 2

2

您的图像正在同步下载，这意味着您正在阻塞主线程（这很糟糕）。相反，在后台线程上运行下载，这将允许主线程以及扩展应用程序的 UI 仍然可以运行。使用您的示例代码，这是在后台运行时的样子：

self.img = [[UIImageView alloc] initWithFrame:CGRectMake(0, 65, self.view.frame.size.width, self.view.frame.size.width-70)];
self.img.animationDuration = 20.0f;
self.img.animationRepeatCount = 0;
[self.img startAnimating];
[self.view addSubview:self.img];

// START ANIMATING YOUR ACTIVITY INDICATOR HERE

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {

    NSArray *images = @[
        [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],
        [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],
        [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],
        [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"URL"]]],
    ];

    dispatch_async(dispatch_get_main_queue(), ^(void) {

        // STOP ANIMATING YOUR ACTIVITY INDICATOR HERE

        [self.img setAnimationImages:images];

    });

});
于 2015-02-13T23:48:39.813 回答
1

下载开始时编写以下代码： UIActivityIndi​​catorView *spinner = [[UIActivityIndi​​catorView alloc] initWithActivityIndi​​catorStyle:UIActivityIndi​​catorViewStyleGray] ; spinner.frame = CGRectMake(0, 0, 320, 50); [微调开始动画];

下载结束时编写此代码：[spinner stopAnimating];

于 2015-02-14T04:45:02.233 回答