从文件异步加载图像

如果您要做的只是保持UI线程可用,请设置一个简短的方法将其加载到后台,并在完成后更新imageView:

-(void)backgroundLoadImageFromPath:(NSString*)path {
    UIImage *newImage = [UIImage imageWithContentsOfFile:path];
    [myImageView performSelectorOnMainThread:@selector(setImage:) withObject:newImage waitUntilDone:YES];
}

这个假设 myImageView 是类的成员变量。现在,只需在后台从任何线程运行它:

[self performSelectorInBackground:@selector(backgroundLoadImageFromPath:) withObject:path];

注意,在 backgroundLoadImageFromPath setImage: 选择器完成,否则后台线程的自动释放池可能会在 设置图像:

您可以为此目的使用NSInvocationOperation: 呼叫

NSOperationQueue *queue = [NSOperationQueue new];
NSInvocationOperation *operation = [[NSInvocationOperation alloc]
                                    initWithTarget:self
                                    selector:@selector(loadImage:)
                                    object:imagePath];
[queue addOperation:operation];

哪里:

- (void)loadImage:(NSString *)path

{

NSData* imageFileData = [[NSData alloc] initWithContentsOfFile:path];
 UIImage* image = [[UIImage alloc] initWithData:imageFileData];

[self performSelectorOnMainThread:@selector(displayImage:) withObject:image waitUntilDone:NO];
}

- (void)displayImage:(UIImage *)image
{
    [imageView setImage:image]; //UIImageView
}