从UIImagePickerController调整UIImage的大小

Question

我目前正在使用此代码拍照

- (void) cameraButtonSelected
{
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.allowsEditing = YES;
    picker.sourceType = UIImagePickerControllerSourceTypeCamera;

    [self presentViewController:picker animated:YES completion:NULL];
}

我允许用户编辑照片，但是当我因某种原因使用此委托方法时，UIImagePickerController在用户按下“使用照片”后不会从视图中删除

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

我想知道

1. 如何在按下“使用照片”按钮后从视图中删除UIImagePickerController
2. 我如何调整刚刚拍摄的照片的大小，因为我需要一个较小的变体发送到我的服务器

Answer 1

您可以通过查询信息词典中的UIImagePickerControllerEditedImage来获取图像。并从View中删除ImagePicker只是解雇选择器。这是调整大小的代码。只需使用您的图像实例调用它

您可以使用此功能将图像缩放到特定大小

- (UIImage *) scaleImage:(UIImage*)image toSize:(CGSize)newSize {
    //UIGraphicsBeginImageContext(newSize);
    // In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
    // Pass 1.0 to force exact pixel size.
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

所以你的最终代码应该是这样的

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {    
    [picker dismissViewControllerAnimated:YES completion:Nil]; 
    UIImage *image = info[UIImagePickerControllerEditedImage];
    image = [self scaleImage:image toSize:CGSizeMake(200,200)]; // or some other size
}

Answer 2

很简单，你可以在stackoverflow上搜索它

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
 UIImage *tempImage=[info objectForKey:UIImagePickerControllerEditedImage];

 [self.dealImageView setImage:[self imageWithImage:tempImage convertToSize:CGSizeMake(200, 200)]];

 [self dismissViewControllerAnimated:YES completion:nil];

}

- (UIImage *)imageWithImage:(UIImage *)image convertToSize:(CGSize)size {

  UIGraphicsBeginImageContext(size);
  [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
  UIImage *destImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return destImage;
}

whats-the-easiest-way-to-resize-optimize-an-image-size-with-the-iphone-sdk

resizing-and-cropping-a-uiimage

Answer 3

1. 用你的[self dismissModalViewControllerAnimated:YES completion:nil]方法调用- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info。这是任何模态视图的常见做法。
2. 这个问题可能比你想象的要复杂得多。有许多方法可以在iOS中调整照片大小，您使用的代码实际上取决于您的需求。但是，您可以查看此博客文章，以了解照片大小调整。它非常全面，我建议您在编写任何代码之前阅读它。 http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way/ 话虽如此，这是实现调整大小的一种非常简单的方法： The simplest way to resize an UIImage?