iPhone - UIImagePickerController -> 将图片保存到应用程序文件夹

Question

我有一个iPhone应用程序，使用UIImagePickerController。作为sourceType，我有：

• UIImagePickerControllerSourceTypePhotoLibrary（照片图库）
• UIImagePickerControllerSourceTypeCamera（相机拍摄）
• UIImagePickerControllerSourceTypeSavedPhotosAlbum（已保存的照片）

所以用户可以从照片图库或相机照片中拍照或选择照片。

图片将显示在UIImageView中。如果用户关闭应用程序，则应保存图像。因此，对于文本字段，我使用NSUserDefaults。我知道，使用NSData将图像保存在NSUSerDefaults中不是一个好的方法，因此我想将图像保存/复制到一个由我的应用程序控制的文件夹中，类似于NSUserDefaults。

我该如何做？我想要保存它，然后我可以将文件路径写入我的NSUserDefaults并在应用程序启动时读取它。

提前感谢您的帮助和祝好！

- Tim

Answer 1

您可以在 UIImagePickerControllerDelegate 委托实现中使用以下代码

- (void) imagePickerController:(UIImagePickerController *)picker
 didFinishPickingMediaWithInfo:(NSDictionary *)info {

    //obtaining saving path
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *imagePath = [documentsDirectory stringByAppendingPathComponent:@"latest_photo.png"];

    //extracting image from the picker and saving it
    NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];   
    if ([mediaType isEqualToString:@"public.image"]){
        UIImage *editedImage = [info objectForKey:UIImagePickerControllerEditedImage];
        NSData *webData = UIImagePNGRepresentation(editedImage);
        [webData writeToFile:imagePath atomically:YES];
    }
}

更新

XueYu 提供的 Swift 3.0 代码:

这里将图像保存为 JPEG 格式，但也可以保存为 PNG 格式。0.0 参数代表压缩质量最低，如果要获得最佳质量，请使用 1.0。

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

    //obtaining saving path
    let fileManager = FileManager.default
    let documentsPath = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first
    let imagePath = documentsPath?.appendingPathComponent("image.jpg")

    // extract image from the picker and save it
    if let pickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
        try! UIImageJPEGRepresentation(pickedImage, 0.0)?.write(to: imagePath!)
    }
    self.dismiss(animated: true, completion: nil)        
}

- knuku

---

我需要使用[info objectForKey:UIImagePickerControllerOriginalImage];而非UIImagePickerControllerEditedImage。 - Brody Robertson

确切地说，这取决于您是否允许编辑，picker.allowsEditing = YES; - khunshan

假设该图像为 PNG 格式（或至少不关心将图像保存为 PNG）。 - Andy

Answer 2

根据您想要保存的文件格式，您可以使用以下方法：

[UIImagePNGRepresentation(image) writeToFile:path atomically:YES];

或者

[UIImageJPEGRepresentation(image) writeToFile:path atomically:YES];

- Björn Marschollek

Answer 3

这是将UIImage保存到文档目录的代码。您可以在didFinishPickingImage代理方法中使用此代码：

// Create paths to output images
NSString  *pngPath = [NSHomeDirectory();
stringByAppendingPathComponent:@"Documents/Test.png"];
NSString  *jpgPath = [NSHomeDirectory();
stringByAppendingPathComponent:@"Documents/Test.jpg"];

// Write a UIImage to JPEG with minimum compression (best quality)
// The value 'image' must be a UIImage object
// The value '1.0' represents image compression quality as value from 0.0 to 1.0
[UIImageJPEGRepresentation(image, 1.0) writeToFile:jpgPath atomically:YES];

// Write image to PNG
[UIImagePNGRepresentation(image) writeToFile:pngPath atomically:YES];

// Let's check to see if files were successfully written...

// Create file manager
NSError *error;
NSFileManager *fileMgr = [NSFileManager defaultManager];

// Point to Document directory
NSString *documentsDirectory = [NSHomeDirectory();
stringByAppendingPathComponent:@"Documents"];

// Write out the contents of home directory to console
NSLog(@"Documents directory: %@", [fileMgr contentsOfDirectoryAtPath:documentsDirectory error:&error]);

编辑

您也可以使用：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

查找应用程序文档目录的路径，而不是NSHomeDirectory。

- iHS

---

@iHS 我需要从API中检索图像并将其存储在应用程序中，我能否使用相同的代码保存图像？ - arshad

Answer 4

更新knuku的Swift 3.0答案

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

    //obtaining saving path
    let fileManager = FileManager.default
    let documentsPath = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first
    let imagePath = documentsPath?.appendingPathComponent("image.jpg")

    // extract image from the picker and save it
    if let pickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
        try! UIImageJPEGRepresentation(pickedImage, 0.0)?.write(to: imagePath!)
    }
    self.dismiss(animated: true, completion: nil)        
}

这里图像被保存为JPEG格式，但你也可以将其保存为PNG格式。参数0.0代表压缩质量最低，如果想要获得最佳效果，请使用1.0。

- XueYu