问如何将图像URL保存到图片库并随后使用保存的图像

EN

    UIImageWriteToSavedPhotosAlbum(yourImage, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);



- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error != NULL)
    {
        // handle error
    }
    else 
    {
        // handle ok status
    }
}

// load data in new thread
[NSThread detachNewThreadSelector:@selector(downloadImage) toTarget:self withObject:nil];

- (void)downloadImage
{

    // network animation on
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

    // create autorelease pool
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; 

   // save image from the web
    UIImageWriteToSavedPhotosAlbum([UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"your_image_address.com"]]], self, @selector(image:didFinishSavingWithError:contextInfo:), nil);

    [self performSelectorOnMainThread:@selector(imageDownloaded) withObject:nil waitUntilDone:NO ];  

    [pool drain];       

}

- (void)imageDownloaded
{

    // network animation off
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

    // do whatever you need to do after 
}