ios – 如何获得UIImage的dpi / ppi？

#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,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.

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.有关更多信息,请参见http://iosdevelopertips.com/data-file-management/get-image-data-including-depth-color-model-dpi-and-more.html.