不改变button大小，扩大点击范围

如图所示:

假设我们要做类似上图的一个效果，点击关闭图片的时候关闭窗口。但是为了整体UI效果，按钮做的小了一些，这时候会影响点击效果。(诚然，有的时候你觉得按钮做大一点不就行了吗，我也是这么想的，可是产品和UI会用一千个理由怼回来的)现在我贴出一个已经测试过的方法供大家使用。

我们将要实现的效果如图:
效果图

1.新建一个UIButton的Category – UIButton+EnlargeEdge
UIButton+EnlargeEdge.h

#import <UIKit/UIKit.h>
#import <objc/runtime.h>

@interface UIButton (EnlargeEdge)

/** 设置可点击范围到按钮边缘的距离 */
- (void)setEnlargeEdge:(CGFloat)size;

/** 设置可点击范围到按钮上、右、下、左的距离 */
- (void)setEnlargeEdgeWithTop:(CGFloat)top right:(CGFloat)right bottom:(CGFloat)bottom left:(CGFloat)left;

@end

UIButton+EnlargeEdge.m

#import "UIButton+EnlargeEdge.h"

static char topNameKey;
static char rightNameKey;
static char bottomNameKey;
static char leftNameKey;

@implementation UIButton (EnlargeEdge)

- (void)setEnlargeEdge:(CGFloat)size {
    objc_setAssociatedObject(self, &topNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, &rightNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, &bottomNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, &leftNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (void)setEnlargeEdgeWithTop:(CGFloat)top right:(CGFloat)right bottom:(CGFloat)bottom left:(CGFloat)left {
    objc_setAssociatedObject(self, &topNameKey, [NSNumber numberWithFloat:top], OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, &rightNameKey, [NSNumber numberWithFloat:right], OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, &bottomNameKey, [NSNumber numberWithFloat:bottom], OBJC_ASSOCIATION_COPY_NONATOMIC);
    objc_setAssociatedObject(self, &leftNameKey, [NSNumber numberWithFloat:left], OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (CGRect)enlargedRect {
    NSNumber* topEdge = objc_getAssociatedObject(self, &topNameKey);
    NSNumber* rightEdge = objc_getAssociatedObject(self, &rightNameKey);
    NSNumber* bottomEdge = objc_getAssociatedObject(self, &bottomNameKey);
    NSNumber* leftEdge = objc_getAssociatedObject(self, &leftNameKey);
    if (topEdge && rightEdge && bottomEdge && leftEdge) {
        return CGRectMake(self.bounds.origin.x - leftEdge.floatValue,
                          self.bounds.origin.y - topEdge.floatValue,
                          self.bounds.size.width + leftEdge.floatValue + rightEdge.floatValue,
                          self.bounds.size.height + topEdge.floatValue + bottomEdge.floatValue);
    } else {
        return self.bounds;
    }
}

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
    CGRect rect = [self enlargedRect];
    if (CGRectEqualToRect(rect, self.bounds)) {
        return [super pointInside:point withEvent:event];
    }
    return CGRectContainsPoint(rect, point) ? YES : NO;
}

@end

2.ViewController.m测试代码

#import "ViewController.h"
#import "UIButton+EnlargeEdge.h"

@interface ViewController ()

@property (nonatomic, strong) UIButton *button1;
@property (nonatomic, strong) UIButton *button2;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.button1 = [UIButton buttonWithType:UIButtonTypeCustom];
    self.button1.frame = CGRectMake(150, 100, self.view.bounds.size.width-300, self.view.bounds.size.width-300);
    self.button1.backgroundColor = [UIColor blueColor];
    self.button1.tag = 1001;
    [self.button1 addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
    [self.button1 setEnlargeEdge:10];
    [self.view addSubview:self.button1];

    self.button2 = [UIButton buttonWithType:UIButtonTypeCustom];
    self.button2.frame = CGRectMake(150, 300, self.view.bounds.size.width-300, self.view.bounds.size.width-300);
    self.button2.backgroundColor = [UIColor greenColor];
    self.button2.tag = 1002;
    [self.button2 addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
    [self.button2 setEnlargeEdgeWithTop:50 right:50 bottom:200 left:50];
    [self.view addSubview:self.button2];
}

- (void)buttonClick:(UIButton *)btn {
    NSString *msg = nil;
    if (btn.tag == 1001) {
        msg = @"点击button1";
    } else if (btn.tag == 1002) {
        msg = @"点击button2";
    }
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:nil message:msg preferredStyle:UIAlertControllerStyleActionSheet];
    UIAlertAction *action = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleDefault handler:nil];
    [alertController addAction:action];
    [self presentViewController:alertController animated:YES completion:nil];
}

@end

代码就这么多，就不贴demo了，有需要的直接copy代码就好了

不改变button大小，扩大点击范围

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