關聯

#import <UIKit/UIKit.h>

@interface UIButton (HitEdgeInsets)

@property(nonatomic, assign) CGFloat hitTestEdgeInsets;

- (void)setHitEdgeWithTop:(CGFloat)top left:(CGFloat)left bottom:(CGFloat)bottom right:(CGFloat)right;

- (void)setHitEdgeWithRect;
@end

#import "UIButton+HitEdgeInsets.h"

@implementation UIButton (HitEdgeInsets)

static char topEdgeKey;
static char leftEdgeKey;
static char bottomEdgeKey;
static char rightEdgeKey;

- (void)setHitTestEdgeInsets:(CGFloat)hitTestEdgeInsets {
    [self setHitEdgeWithTop:hitTestEdgeInsets left:hitTestEdgeInsets bottom:hitTestEdgeInsets right:hitTestEdgeInsets];
}

- (CGFloat)hitTestEdgeInsets {
     //獲取相關聯的對象
    return [(NSNumber *)objc_getAssociatedObject(self, &topEdgeKey) floatValue];
}

- (void)setHitEdgeWithTop:(CGFloat)top left:(CGFloat)left bottom:(CGFloat)bottom right:(CGFloat)right {
    objc_setAssociatedObject(self, &topEdgeKey, [NSNumber numberWithFloat:top], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    objc_setAssociatedObject(self, &leftEdgeKey, [NSNumber numberWithFloat:left], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    objc_setAssociatedObject(self, &bottomEdgeKey, [NSNumber numberWithFloat:bottom], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    objc_setAssociatedObject(self, &rightEdgeKey, [NSNumber numberWithFloat:right], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (void)setHitEdgeWithRect {
    objc_setAssociatedObject(self, &topEdgeKey, [NSNumber numberWithFloat:30], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    objc_setAssociatedObject(self, &leftEdgeKey, [NSNumber numberWithFloat:30], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    objc_setAssociatedObject(self, &bottomEdgeKey, [NSNumber numberWithFloat:30], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    objc_setAssociatedObject(self, &rightEdgeKey, [NSNumber numberWithFloat:30], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (CGRect)enlargeRect {
    NSNumber *topEdge = objc_getAssociatedObject(self, &topEdgeKey);
    NSNumber *leftEdge = objc_getAssociatedObject(self, &leftEdgeKey);
    NSNumber *bottomEdge = objc_getAssociatedObject(self, &bottomEdgeKey);
    NSNumber *rightEdge = objc_getAssociatedObject(self, &rightEdgeKey);
    if (topEdge&&leftEdge&&bottomEdge&&rightEdge) {
        CGRect enlargeRect = CGRectMake(self.bounds.origin.x-leftEdge.floatValue, self.bounds.origin.y-topEdge.floatValue, self.width+leftEdge.floatValue+rightEdge.floatValue, self.height+topEdge.floatValue+bottomEdge.floatValue);
        return enlargeRect;
    }else {
        return self.bounds;
    }
}

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
    if (self.alpha<=0.01||!self.userInteractionEnabled||self.hidden) {
        return nil;
    }
    
    CGRect enlargeRect = [self enlargeRect];
    return CGRectContainsPoint(enlargeRect, point)?self:nil;
}