我正在下载一组图像来创建动画。如何使下载开始时显示事件指示器以及下载完成时隐藏事件指示器。
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];
最佳答案
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 仍然运行。使用您的示例代码,在后台运行时如下所示:
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];
});
});
关于ios - 下载图像时的事件指示器 iOS,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28509926/