iOS 从相机或相册获取图片并裁剪

/load user image  
- (void)UesrImageClicked 
{ UIActionSheet *sheet; // 判断是否支持相机  if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) { sheet  = [[UIActionSheet alloc] initWithTitle:@"选择图像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"拍照", @"从相册选择", nil]; } else { sheet = [[UIActionSheet alloc] initWithTitle:@"选择图像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"从相册选择", 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; // 判断是否支持相机  if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) { switch (buttonIndex) { case 0: return; case 1: //相机  sourceType = UIImagePickerControllerSourceTypeCamera; break; case 2: //相册  sourceType = UIImagePickerControllerSourceTypePhotoLibrary; break; } } else { if (buttonIndex == 0) { return; } else { sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum; } } // 跳转到相机或相册页面  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;// 判断是否支持相机if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){sheet  = [[UIActionSheet alloc] initWithTitle:@"选择图像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"拍照", @"从相册选择", nil];}else {sheet = [[UIActionSheet alloc] initWithTitle:@"选择图像" delegate:self cancelButtonTitle:nil destructiveButtonTitle:@"取消" otherButtonTitles:@"从相册选择", 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;// 判断是否支持相机if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {switch (buttonIndex) {case 0:return;case 1: //相机sourceType = UIImagePickerControllerSourceTypeCamera;break;case 2: //相册sourceType = UIImagePickerControllerSourceTypePhotoLibrary;break;}}else {if (buttonIndex == 0) {return;} else {sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;}}// 跳转到相机或相册页面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];}

 

返回的图像并不是正方形，显示在用户头像的View里面产生明显的拉伸。研究了很久各种裁剪算法，甚至想创建一个view来处理。突然发现代码中从相机、相册获取图片时采用的的

UIImagePickerControllerOriginalImage

于是跟踪进去一看：

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

 

将 UIImagePickerControllerOriginalImage 改为UIImagePickerControllerEditedImage，万事搞定。