图片保存到手机相册

// Adds a photo to the saved photos album.  The optional completionSelector should have the form:
//  - (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;
UIKIT_EXTERN void UIImageWriteToSavedPhotosAlbum(UIImage *image, __nullable id completionTarget, __nullable SEL completionSelector, void * __nullable contextInfo);

// Is a specific video eligible to be saved to the saved photos album?

UIKIT_EXTERN BOOL UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(NSString *videoPath) NS_AVAILABLE_IOS(3_1);

// Adds a video to the saved photos album. The optional completionSelector should have the form:
//  - (void)video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;
UIKIT_EXTERN void UISaveVideoAtPathToSavedPhotosAlbum(NSString *videoPath, __nullable id completionTarget, __nullable SEL completionSelector, void * __nullable contextInfo) NS_AVAILABLE_IOS(3_1);

//保存按钮的事件响应方法
- (void)savePictureToAlbum:(NSString *)URLString
{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"提示" message:@"确定要保存到相册吗？" preferredStyle:UIAlertControllerStyleActionSheet];

[alert addAction:[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil]];
[alert addAction:[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {

NSURLCache *cache =[NSURLCache sharedURLCache];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:URLString]];
NSData *imgData = [cache cachedResponseForRequest:request].data;
UIImage *image = [UIImage imageWithData:imgData];
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

}]];
[self presentViewController:alert animated:YES completion:nil];
}

//保存按钮的事件响应方法
- (void)savePictureToAlbum{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"提示" message:@"确定要保存到相册吗？" preferredStyle:UIAlertControllerStyleActionSheet];

[alert addAction:[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil]];
[alert addAction:[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {

UIImageView *imageView = [[UIImageView alloc]init];
[imageView setImageWithURL:[NSURL URLWithString:self.model.thumbURL]];
UIImage *image = imageView.image;
//

//        NSURLCache *cache =[NSURLCache sharedURLCache];
//        NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:URLString]];
//        NSData *imgData = [cache cachedResponseForRequest:request].data;
//        UIImage *image = [UIImage imageWithData:imgData];

UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

}]];
[self presentViewController:alert animated:YES completion:nil];
}