Created
March 27, 2014 23:19
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A quick function for determining an image's file type by its first couple of bytes
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@import MobileCoreServices; | |
static CFStringRef UTTypeForImageData(NSData *data) { | |
const unsigned char * bytes = [data bytes]; | |
if (data.length >= 8) { | |
if (bytes[0] == 0x89 && bytes[1] == 0x50 && bytes[2] == 0x4E && bytes[3] == 0x47 && bytes[4] == 0x0D && bytes[5] == 0x0A && bytes[6] == 0x1A && bytes[7] == 0x0A) { | |
return kUTTypePNG; | |
} | |
} | |
if (data.length >= 4) { | |
if (bytes[0] == 0xFF && bytes[1] == 0xD8 && bytes[2] == 0xFF && bytes[3] == 0xE0) { | |
return kUTTypeJPEG; | |
} | |
} | |
if (data.length >= 3) { | |
if (bytes[0] == 0x47 && bytes[1] == 0x49 && bytes[2] == 0x46) { | |
return kUTTypeGIF; | |
} else if (bytes[0] == 0x49 && bytes[1] == 0x49 && bytes[2] == 0x2A) { | |
return kUTTypeBMP; | |
} | |
} | |
if (data.length >= 2) { | |
if (bytes[0] == 0x42 && bytes[1] == 0x4D) { | |
return kUTTypeBMP; | |
} | |
} | |
return nil; | |
} |
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this is handy in js too