上传时压缩图像 [英] Compress image at the time of uploading

问题描述

我想在服务器上传图片。
但在上传之前，我想压缩该图像，然后上传到服务器。我不想上传超过2 MB的图像。
我已经使用过这个逻辑但是如果图像大小很大那么它就不会运行。在处理期间，循环和占用的内存增加到1 gb。

I want to upload image on server. But before uploading i want to compress that image and then upload to server. I dont want to upload image more than 2 mb. I have used this logic but if image size is to large then it runs no. of loops and also occupied memory increased to 1 gb during processing.

 double compressionRatio=1;
 NSData *imgData=UIImagePNGRepresentation(proImage.image,compressionRatio);
   while ([imgData length]>50000) {
    compressionRatio=compressionRatio*50;
    imgData=UIImageJPEGRepresentation(proImage.image,compressionRatio);
   }

推荐答案

请看看< a href =https://developer.apple.com/library/iOS/documentation/UIKit/Reference/UIKitFunctionReference/Reference/reference.html#//apple_ref/doc/uid/TP40006894-CH3-SW9\"rel =nofollow > UIImageJPEGRepresentation文档。

NSData * UIImageJPEGRepresentation (
   UIImage *image,
   CGFloat compressionQuality
);

compressionQuality = 0.0; ... max compression
compressionQuality = 1.0; ... min compression

您可以尝试类似：

NSData *imgData=UIImagePNGRepresentation(proImage.image,compressionRatio);

if ([NSData length] > maxSizeThatYouWant) {

    CGFloat compressionNeeded = (CGFloat)[NSData length]/(CGFloat)maxSizeThatYouWant;

    imgData=UIImageJPEGRepresentation(proImage.image,compressionNeeded);
}

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