问题
I need to know which image file type was used in the file i loaded with "initWithContentsOfFie" because i don't want to trust the file extension.
Unfortunately i can't find anything about the format in NSImage and NSImageRep,
回答1:
NSImage doesn't keep that information, because it's of no further use. You'll need to drop down to CGImageSource to get the info you want.
来源：https://stackoverflow.com/questions/3590003/how-can-i-find-the-file-type-after-loading-nsimage-withcontentsoffile