如何在iphone应用程序中压缩保存的图像[重复]

Question

我有一个应用程序，我可以在其中捕获图像，它工作正常，但我想减小我从网上搜索的图像的大小，我发现了一些代码在这里

这是我的代码在捕获图像时工作正常

NSString *type = [info objectForKey:UIImagePickerControllerMediaType];

UIImage *pickedImage = [info objectForKey:UIImagePickerControllerOriginalImage];

NSData *imageData = UIImagePNGRepresentation(pickedImage);

NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

我想减小拾取图像的大小，我得到了以下代码，但我没有像使用 newSize 那样使用它，而是使用原始图像进行压缩

UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();   

Answer 1

你能做的是……

NSString *type = [info objectForKey:UIImagePickerControllerMediaType];

UIImage *pickedImage = [info objectForKey:UIImagePickerControllerOriginalImage];

 CGSize sizeCropped = CGSizeMake(602, 450);//you can adjust any size here...

 pickedImage = [yourclassname imageWithImage:pickedImage scaledToSize:sizeCropped];//call below function...




+ (UIImage*)imageWithImage:(UIImage*)image
          scaledToSize:(CGSize)newSize;
{
UIGraphicsBeginImageContext( newSize );
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

return newImage;
 }

让我知道它是否有效！！！！

编码愉快！！！！！

Answer 2

+(UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize;
{
    UIGraphicsBeginImageContext( newSize ); 
    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

您可以使用这些代码行在需要压缩图像的地方调用此函数。

    CGSize firstSize = CGSizeMake(210.0,210.0);
    UIImage *compImage=[mainclass imageWithImage:image scaledToSize:firstSize];

Answer 3

如果你想用新的尺寸保存新的图像，那么在你的代码之后用下面的行将该图像添加到库中..

UIImageWriteToSavedPhotosAlbum(UIImage *image, id completionTarget, SEL completionSelector, void *contextInfo);

前：

UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil);