网页设计教程23/淘宝seo什么意思

       今天遇到一个用户头像上传的问题，需要从相册或者相机中读取图片。代码很简单，抽取关键部分，如下：

 

//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];}

创建一张表单，选择相机或者相册，然后用回调函数处理返回的图片。

但是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 

 

恍然大悟，很简单，用UIImagePickerControllerEditedImage，万事搞定。