Created
February 27, 2016 23:09
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iOS: How to retrieve image dimensions without loading CGImage into memory
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| // This method requires ImageIO.framework | |
| #import <ImageIO/ImageIO.h> | |
| - (CGSize)sizeOfImageAtURL:(NSURL *)imageURL | |
| { | |
| // With CGImageSource we avoid loading the whole image into memory | |
| CGSize imageSize = CGSizeZero; | |
| CGImageSourceRef source = CGImageSourceCreateWithURL((CFURLRef)imageURL, NULL); | |
| if (source) { | |
| NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:NO] forKey:(NSString *)kCGImageSourceShouldCache]; | |
| NSDictionary *properties = (NSDictionary *)CGImageSourceCopyPropertiesAtIndex(source, 0, (CFDictionaryRef)options); | |
| if (properties) { | |
| NSNumber *width = [properties objectForKey:(NSString *)kCGImagePropertyPixelWidth]; | |
| NSNumber *height = [properties objectForKey:(NSString *)kCGImagePropertyPixelHeight]; | |
| if ((width != nil) && (height != nil)) | |
| imageSize = CGSizeMake(width.floatValue, height.floatValue); | |
| CFRelease(properties); | |
| } | |
| CFRelease(source); | |
| } | |
| return imageSize; | |
| } |
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