iOS 從相機或相簿擷取圖片並裁剪

   今天遇到一個帳戶圖片上傳的問題，需要從相簿或者相機中讀取圖片。代碼很簡單，抽取關鍵區段，如下：

 

/load user image  - (void)UesrImageClicked {     UIActionSheet *sheet;          // 判斷是否支援相機      if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])     {         sheet  = [[UIActionSheet alloc] initWithTitle:@"選擇映像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"拍照", @"從相簿選擇", nil];     }     else {         sheet = [[UIActionSheet alloc] initWithTitle:@"選擇映像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"從相簿選擇", nil];     }          sheet.tag = 255;          [sheet showInView:self.view]; }   #pragma mark - action sheet delegte  - (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {     if (actionSheet.tag == 255) {         NSUInteger sourceType = UIImagePickerControllerSourceTypePhotoLibrary;         // 判斷是否支援相機          if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {             switch (buttonIndex) {                 case 0:                     return;                 case 1: //相機                      sourceType = UIImagePickerControllerSourceTypeCamera;                     break;                 case 2: //相簿                      sourceType = UIImagePickerControllerSourceTypePhotoLibrary;                     break;             }         }         else {             if (buttonIndex == 0) {                 return;             } else {                 sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;             }         }         // 跳轉到相機或相簿頁面          UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];         imagePickerController.delegate = self;         imagePickerController.allowsEditing = YES;         imagePickerController.sourceType = sourceType;                  [self presentViewController:imagePickerController animated:YES completion:^{}];     } }  #pragma mark - image picker delegte  - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {     [picker dismissViewControllerAnimated:YES completion:^{}];          UIImage *image = [info UIImagePickerControllerOriginalImage];         userImageView.image = image;          NSData *imageData = UIImageJPEGRepresentation(image, COMPRESSED_RATE);     UIImage *compressedImage = [UIImage imageWithData:imageData];          [HttpRequestManager uploadImage:compressedImage httpClient:self.httpClient delegate:self];      } //load user image- (void)UesrImageClicked{    UIActionSheet *sheet;       // 判斷是否支援相機    if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])    {        sheet  = [[UIActionSheet alloc] initWithTitle:@"選擇映像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"拍照", @"從相簿選擇", nil];    }    else {        sheet = [[UIActionSheet alloc] initWithTitle:@"選擇映像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"從相簿選擇", nil];    }       sheet.tag = 255;       [sheet showInView:self.view];}#pragma mark - action sheet delegte- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex{    if (actionSheet.tag == 255) {        NSUInteger sourceType = UIImagePickerControllerSourceTypePhotoLibrary;        // 判斷是否支援相機        if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {            switch (buttonIndex) {                case 0:                    return;                case 1: //相機                    sourceType = UIImagePickerControllerSourceTypeCamera;                    break;                case 2: //相簿                    sourceType = UIImagePickerControllerSourceTypePhotoLibrary;                    break;            }        }        else {            if (buttonIndex == 0) {                return;            } else {                sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;            }        }        // 跳轉到相機或相簿頁面        UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];        imagePickerController.delegate = self;        imagePickerController.allowsEditing = YES;        imagePickerController.sourceType = sourceType;               [self presentViewController:imagePickerController animated:YES completion:^{}];    }}#pragma mark - image picker delegte- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{ [picker dismissViewControllerAnimated:YES completion:^{}];       UIImage *image = [info UIImagePickerControllerOriginalImage];       userImageView.image = image;       NSData *imageData = UIImageJPEGRepresentation(image, COMPRESSED_RATE);    UIImage *compressedImage = [UIImage imageWithData:imageData];       [HttpRequestManager uploadImage:compressedImage httpClient:self.httpClient delegate:self];   }

建立一張表單，選擇相機或者相簿，然後用回呼函數處理返回的圖片。

 

但是返回的映像並不是正方形，顯示在帳戶圖片的View裡面產生明顯的展開。研究了很久各種裁剪演算法，甚至想建立一個view來處理。突然發現代碼中從相機、相簿擷取圖片時採用的的

UIImagePickerControllerOriginalImage

於是跟蹤進去一看：

UIKIT_EXTERN NSString *const UIImagePickerControllerMediaType;      // an NSString (UTI, i.e. kUTTypeImage)

UIKIT_EXTERN NSString *const UIImagePickerControllerOriginalImage;  // a UIImage

UIKIT_EXTERN NSString *const UIImagePickerControllerEditedImage;    // a UIImage

UIKIT_EXTERN NSString *const UIImagePickerControllerCropRect;       // an NSValue (CGRect)

UIKIT_EXTERN NSString *const UIImagePickerControllerMediaURL;       // an NSURL

UIKIT_EXTERN NSString *const UIImagePickerControllerReferenceURL        NS_AVAILABLE_IOS(4_1);  // an NSURL that references an

 

恍然大悟，很簡單，用UIImagePickerControllerEditedImage，萬事搞定。