shap view with a image

gistfile1.txt

@interface UIView(ImageMask)
- (void)setMaskImage:(UIImage *)maskImage;
@end

@implementation UIView(ImageMask)
- (void)setMaskImage:(UIImage *)maskImage {
    objc_setAssociatedObject(self, @selector(setMaskImage:), maskImage, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    UIImageView *view = [[UIImageView alloc]initWithImage:maskImage];
    view.frame = self.bounds;
    self.layer.mask = view.layer;
    self.layer.masksToBounds = YES;
    
    [[self class] setMethod:@selector(blankSetFrame:) withIMP:@selector(setFrame:)];
    [[self class] setMethod:@selector(setFrame:) withIMP:@selector(insertSetFrame:)];
}
- (UIImage *)maskImage {
    return objc_getAssociatedObject(self, @selector(setMaskImage:));
}
- (void)updateMask {
    if ([self maskImage]) {
        UIImageView *view = [[UIImageView alloc]initWithImage:[self maskImage]];
        view.frame = self.bounds;
        self.layer.mask = view.layer;
        self.layer.masksToBounds = YES;
    }
}
- (void)blankSetFrame:(CGRect)frame {
}
- (void)insertSetFrame:(CGRect)frame {
    [self blankSetFrame:frame];
    [self updateMask];
}
@end



@interface NSObject (categoryProperty)
+ (void)setMethod:(SEL)selector withIMP:(SEL)other;
@end

@implementation NSObject (categoryProperty)
+ (void)setMethod:(SEL)selector withIMP:(SEL)other {
    Method md = class_getClassMethod([self class], selector);
    BOOL isClass = YES;
    if (!md) {
        md = class_getInstanceMethod([self class], selector);
        isClass = NO;
    }
    
    IMP imp = isClass?[[self class] methodForSelector:other]:[[self class] instanceMethodForSelector:other];//判断是不是class方法很重要，否则会失败
    if (md && imp) {
        method_setImplementation(md, imp);
    }
}

@end