将UIImage大小减小到可管理的大小（减少字节） [英] Reduce UIImage size to a manageable size (reduce bytes)

问题描述

我想减少由设备捕获的图像的字节数，因为我相信 _imageScaledToSize 不会减少图片的字节数（或它？） - 我想在本地词典对象中存储图像的缩略图，并且不能将全尺寸图像放在字典中。任何想法？

I want to reduce the number of bytes of an image captured by the device, since i believe the _imageScaledToSize does not reduce the number of bytes of the picture (or does it?) - i want to store a thumbnail of the image in a local dictionary object and can't afford to put full size images in the dictionary. Any idea?

推荐答案

如果您只想压缩UIImage，可以使用

If you wish to simply compress your UIImage, you can use

NSData *dataForPNGFile = UIImagePNGRepresentation(yourImage);

生成您的图像的NSData版本，编码为PNG（容易插入NSDictionary或写入磁盘），或者您可以使用

to generate an NSData version of your image encoded as a PNG (easily inserted into an NSDictionary or written to disk), or you can use

NSData *dataForPNGFile = UIImageJPEGRepresentation(yourImage, 0.9f);

做同样的，只有JPEG格式。第二个参数是JPEG的图像质量。

to do the same, only in a JPEG format. The second parameter is the image quality of the JPEG. Both of these should produce images that are smaller, memory-wise, than your UIImage.

使用已发布的方法调整UIImage的大小以创建较小的缩略图（以像素为单位）是一个更小的缩略图有点棘手。 _imageScaledToSize来自私人API，我强烈建议你不要使用它。有关在已记录的方法中工作的方法，请参阅此帖< a>。

Resizing a UIImage to create a smaller thumbnail (pixels-wise) using published methods is a little trickier. _imageScaledToSize is from the private API, and I'd highly recommend you not use it. For a means that works within the documented methods, see this post.

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