扩大按钮点击区域

参考自印第安的老斑鸠

参考了很多的文章，主要是有三个方法：

例如：按钮的大小是25pt * 25pt，想要的点击范围是50pt * 50pt，而按钮需要设置一张图片为25pt * 25pt。

如图红色区域为可点击区域，图片为一个加号

• 1、最简单的：直接用setImage方法，准备好你的图片（50px * 50px和75px * 75px），设置button得宽高分别为50pt。

[button setImage:[UIImage imageNamed:@"btnImage"] forState:UIControlStateNormal];
[button setFrame:CGRectMake(0, 0, 50, 50)]

按钮图片

• 2、建立UIButton分类，通过重写hitTest方法来实现扩大按钮的点击范围。
  上代码：

.m文件

#import "UIButton+EnlargeButtonArea.h"
#import <objc/runtime.h>

@implementation UIButton (EnlargeButtonArea)

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

- (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;
    }
}

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
    CGRect rect = [self enlargedRect];
    if (CGRectEqualToRect(rect, self.bounds)) {
        return [super hitTest:point withEvent:event];
    }
    return CGRectContainsPoint(rect, point) ? self : nil;
}
@end

.h文件

#import <UIKit/UIKit.h>

@interface UIButton (EnlargeButtonArea)

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

@end

• 3、第三种和第二种差不多，重写了pointInside方法

.m文件

@dynamic hitTestEdgeInsets;

static const NSString *KEY_HIT_TEST_EDGE_INSETS = @"HitTestEdgeInsets";

-(void)setHitTestEdgeInsets:(UIEdgeInsets)hitTestEdgeInsets {
    NSValue *value = [NSValue value:&hitTestEdgeInsets withObjCType:@encode(UIEdgeInsets)];
    objc_setAssociatedObject(self, &KEY_HIT_TEST_EDGE_INSETS, value, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

-(UIEdgeInsets)hitTestEdgeInsets {
    NSValue *value = objc_getAssociatedObject(self, &KEY_HIT_TEST_EDGE_INSETS);
    if(value) {
        UIEdgeInsets edgeInsets; [value getValue:&edgeInsets]; return edgeInsets;
    }else {
        return UIEdgeInsetsZero;
    }
}

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
    if(UIEdgeInsetsEqualToEdgeInsets(self.hitTestEdgeInsets, UIEdgeInsetsZero) || !self.enabled || self.hidden) {
        return [super pointInside:point withEvent:event];
    }
    
    CGRect relativeFrame = self.bounds;
    CGRect hitFrame = UIEdgeInsetsInsetRect(relativeFrame, self.hitTestEdgeInsets);
    
    return CGRectContainsPoint(hitFrame, point);
}

.h文件

#import <UIKit/UIKit.h>

@interface UIButton (EnlargeButtonArea)

@property(nonatomic, assign) UIEdgeInsets hitTestEdgeInsets;

@end

以上就是我整理的扩大按钮点击范围的三种方式，选择哪一个主要在各位看官，个人推荐第二种。

PS:hitTest还有很多要挖的，老哥扛锹去挖喽。。。