异步加载

for (int i = 0 ; i < 10; i++) {
dispatch_async(dispatch_get_global_queue(0, 0), ^{
// 处理耗时操作的代码块...
UIImage *img = [self getImgeWith:[urlArr objectForIndex:i]];
//通知主线程刷新
dispatch_async(dispatch_get_main_queue(), ^{
//回调或者说是通知主线程刷新，
[myImgV[i] setImage:img];
});

});