UITabBar圆形凸起按钮边缘响应点击

自定义一个UITabbar：

MyUITabBar.h

圆形按钮点击事件需要写一个delegate

#import <UIKit/UIKit.h>

@protocol CenterBtnDelegate <NSObject>

- (void)DidClickCenterBtn;

@end

@interface MyUITabBar : UITabBar

@property (nonatomic, weak)id <CenterBtnDelegate>centerBtnDelegate;

@end

MyUITabBar.m

centerBtn就是要创建的“大按钮”，点击方法用了RAC，跟本功能无关
重点是这个方法

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event

切换当前触摸点的坐标系，使“大按钮”凸起部分可以响应点击事件

#import "MyUITabBar.h"
#import <ReactiveCocoa/ReactiveCocoa.h>

@implementation MyUITabBar
{
    UIButton *centerBtn;
}

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        //中间的圆按钮
        centerBtn = [UIButton buttonWithType:UIButtonTypeCustom];
        centerBtn.frame = CGRectMake(UI_SCREEN_WIDTH/2-kScaleX*30, -(kScaleY*60-49), kScaleX*60, kScaleY*60);
        [centerBtn setImage:[UIImage imageNamed:@"圆按钮"] forState:UIControlStateNormal];
        centerBtn.layer.cornerRadius = centerBtn.frame.size.height/2;
        centerBtn.clipsToBounds = YES;
        [self addSubview:centerBtn];
        
        [[centerBtn rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(id x) {
            if ([self.centerBtnDelegate respondsToSelector:@selector(DidClickCenterBtn)]) {
                [self.centerBtnDelegate DidClickCenterBtn];
            }
        }];
    }
    return self;
}

//重写此方法，让按钮凸起部分也响应点击事件
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
    if (self.isHidden == NO) {//tabbar显示时再执行
        //将当前触摸点切换到“大按钮”的坐标系上
        CGPoint pointInBtn = [self convertPoint:point toView:centerBtn];
        if ([centerBtn pointInside:pointInBtn withEvent:event]) {//如果这个点在“大按钮”内部，那么由“大按钮”来响应此事件
            return centerBtn;
        }else {
            return [super hitTest:point withEvent:event];
        }
    }else {
        return [super hitTest:point withEvent:event];
    }
}

@end

在UITabBarController中用KVC替换一下系统的TabBar

MyUITabBar *myTabBar = [[MyUITabBar alloc]init];
myTabBar.centerBtnDelegate = self;
[self setValue:myTabBar forKeyPath:@"tabBar"];

遵循协议并实现“大按钮”的点击代理方法

centerButton.png