iOS 给category添加属性的小技巧

#import <UIKit/UIKit.h>

@interface UIImage (Rotation)

@property (nonatomic,copy)NSString *isRotation;

#import "UIImage+Rotation.h"
#import <objc/runtime.h>

@implementation UIImage (Rotation)

- (void)setIsRotation:(NSString *)isRotation {
objc_setAssociatedObject(self, @selector(isRotation), isRotation, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
- (NSString *)isRotation {
return objc_getAssociatedObject(self, @selector(isRotation));
}