如何获得UIImage的dpi / ppi？ [英] How to get dpi/ppi of UIImage?

问题描述

如何在iOS中获取图像的dpi / ppi？也许原始图像文件包含这些信息，所以我可以从NSData获得ppi / dpi？
谢谢。

How to get dpi/ppi of image in iOS? Maybe raw image file contains this information, so I can get ppi/dpi from NSData? Thank you.

推荐答案

要从存储在NSData中的图像中提取DPI，请在项目中包含Apple的ImageIO框架，使用以下内容：

To extract DPI from an image stored in NSData, include Apple's ImageIO framework in your project and use the following:

#import <ImageIO/ImageIO.h>

// Set your NSData up
NSData *data = some image data

// Get the DPI of the image
CGImageSourceRef imageRef = CGImageSourceCreateWithData((__bridge CFDataRef)(data), NULL);
CFDictionaryRef imagePropertiesDict = CGImageSourceCopyPropertiesAtIndex(imageRef, 0, NULL);
NSString *dpiHeight = CFDictionaryGetValue(imagePropertiesDict, @"DPIHeight");
NSString *dpiWidth = CFDictionaryGetValue(imagePropertiesDict, @"DPIWidth");

请注意，并非所有图像都包含DPI信息。它可能包含也可能不包含在图像的元数据中。

Note that not all images contain DPI information. It may or may not be included in the image's metadata.

这个答案是基于Flar49的答案，这是正确的，但增强了直接从NSData获取信息。请参阅 http： //iosdevelopertips.com/data-file-management/get-image-data-including-depth-color-model-dpi-and-more.html 了解更多信息。

This answer is based upon Flar49's answer, which is correct, but enhanced to get the information directly from NSData. See http://iosdevelopertips.com/data-file-management/get-image-data-including-depth-color-model-dpi-and-more.html for more information.

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