Question

我有一个名为“保存到相册”的保存按钮。按钮顶部是小UIImageView，用户可以点击下面的按钮将照片的实际尺寸保存到相册。我的问题是当我点击保存按钮时，它显示一个错误：无法将图像保存到相册。

我认为我做得对，但我的经验太有限了。

H档：

#import <UIKit/UIKit.h>

@interface SecondViewController : UIViewController  {

    IBOutlet UIButton *btnReturn;
    IBOutlet UIButton *savePhoto;
    IBOutlet UIImage *saveImage;

}

@property (nonatomic, retain) IBOutlet UIButton *btnReturn;
@property (nonatomic, retain) IBOutlet UIButton *savePhoto;
@property (nonatomic, retain) IBOutlet UIImage *saveImage;

-(IBAction) saveToPhotoAlbum;

@end

以下是我的代码：

-(IBAction) saveToPhotoAlbum{

    NSString *saveMyPhoto=[NSHomeDirectory() stringByAppendingPathComponent:@"sample.png"];

    UIImage *saved=[UIImage imageWithContentsOfFile:saveMyPhoto]; 

    NSData *imageData = [NSData dataWithContentsOfFile:(NSString *)UIImagePNGRepresentation(saved)];
    [imageData writeToFile:(NSString *)saved atomically:YES ];

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

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    UIAlertView *alert;


    if (error)
        alert = [[UIAlertView alloc] initWithTitle:@"Error" 
                                           message:@"Unable to save image to Photo Album." 
                                          delegate:self cancelButtonTitle:@"Ok" 
                                 otherButtonTitles:nil];
    else 
        alert = [[UIAlertView alloc] initWithTitle:@"Success" 
                                           message:@"Image saved to Photo Album." 
                                          delegate:self cancelButtonTitle:@"Ok" 
                                 otherButtonTitles:nil];
    [alert show];
    [alert release];
}

Answer 1

只需创建一个UIImage对象并从文件加载图像。然后只需调用UIIMageWriteToSavedPhotoAlbum函数并将UIImage对象作为第一个参数传递，然后其余部分都可以为NIL。请参阅Apple SDK documentation.

Answer 2

这些线看起来真的很可疑：

NSString *saveMyPhoto=[NSHomeDirectory() stringByAppendingPathComponent:@"sample.png"];
...
UIImage *saved = [UIImage imageWithContentsOfFile:saveMyPhoto]; 
...
[imageData writeToFile:(NSString *)saved atomically:YES ];

你有什么期望这样做？你得到一个图像的路径，加载它，然后再次保存它，但你已经将UIImage转换为NSString并希望它会神奇地变成磁盘上的有效路径？

至于你问的问题，你确定你的图像是有效的图像吗？

无法使用UIImageWriteToSavedPhotosAlbum将图像保存到相册

2 个答案: