08-掌握-GCD线程间通信

OC

//开子线程下载图片

//创建队列(并发)
dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
//异步函数
dispatch_async(queue, ^{
//获取url地址
NSURL *url = [NSURL URLWithString:@"http://www.huabian.com/uploadfile/2015/0914/20150914014032274.jpg"];
//下载图片
NSData *data = [NSData dataWithContentsOfURL:url];
//把二进制数据转换成图片
UIImage *image = [UIImage imageWithData:data];

//返回主线程刷新UI
dispatch_sync(dispatch_get_main_queue(), ^{
self.imageView.image = image;
});
});

swift

//开子线程下载图片
//创建队列(并发)
let queue = dispatch_get_global_queue(0, 0)

//异步函数
dispatch_async(queue) {
//获取url地址
let url = NSURL(string: "http://www.huabian.com/uploadfile/2015/0914/20150914014032274.jpg")
//下载图片
let data = NSData(contentsOfURL: url!)
//把二进制数据转换成图片
let image = UIImage(data: data!)

//返回主线程刷新UI
dispatch_async(dispatch_get_main_queue(), {
self.imageView.image = image
})

}