iOS 自定义底部tabbar加号按钮实现方法

自定义UITabBar替换系统默认的，目的是为了在UITabBar中间位置添加一个“+号按钮”

1、自定义WBTabBar，让其继承自UITabBar，并定义点击事件代理方法。

.h方法里面

#import <UIKit/UIKit.h>

@class WXReleaseTabBar;

@protocol WXReleaseTabBarDelegate <WXReleaseTabBarDelegate>

@optional

- (void)tabBarDidClickPlusButton:(WXReleaseTabBar *)tabBar;

@end

@interface WXReleaseTabBar : UITabBar

@property (nonatomic, weak) id<WXReleaseTabBarDelegate> tabBarDelegate;

@end

.m方法里面

//定义一个按钮

@property (nonatomic, strong) UIButton *plusButton;

然后初始化

- (id)initWithFrame:(CGRect)frame

{

self = [super initWithFrame:frame];

if (self) {

UIButton *plusBtn = [[UIButton alloc] init];

[plusBtn setBackgroundImage:[UIImage imageNamed:@"shareicon"] forState:UIControlStateNormal];

[plusBtn setBackgroundImage:[UIImage imageNamed:@"shareicon"] forState:UIControlStateHighlighted];

[plusBtn setImage:[UIImage imageNamed:@"shareicon"] forState:UIControlStateNormal];

[plusBtn setImage:[UIImage imageNamed:@"shareicon"] forState:UIControlStateHighlighted];

plusBtn.size = plusBtn.currentBackgroundImage.size;

[plusBtn addTarget:self action:@selector(plusClick) forControlEvents:UIControlEventTouchUpInside];

[self addSubview:plusBtn];

self.plusButton = plusBtn;

}

return self;

}

//添加约束

- (void)layoutSubviews

{

[super layoutSubviews];

CGFloat width = self.width;

CGFloat height = self.height;

self.plusButton.center = CGPointMake(width * 0.5, height * 0.5);

CGRect tempRect = self.plusButton.frame;

tempRect.origin.y =  -20;

self.plusButton.frame = tempRect;

int index = 0;

CGFloat tabBarButtonW = width / 5;

CGFloat tabBarButtonH = height;

CGFloat tabBarButtonY = 0;

for (UIView *tabBarButton in self.subviews) {

if (![NSStringFromClass(tabBarButton.class) isEqualToString:@"UITabBarButton"]) continue;

CGFloat tabBarButtonX = index * tabBarButtonW;

if (index >= 2) {

tabBarButtonX += tabBarButtonW;

}

tabBarButton.frame = CGRectMake(tabBarButtonX, tabBarButtonY, tabBarButtonW, tabBarButtonH);

index++;

}

[self bringSubviewToFront:self.plusButton];

}

//重写系统的hitTest方法让处于tabbar外部的按钮部分也可以被点击

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

if (self.isHidden == NO) { // 当前界面 tabBar显示

CGPoint newPoint = [self convertPoint:point toView:self.plusButton];

if ( [self.plusButton pointInside:newPoint withEvent:event]) { // 点 属于按钮范围

return self.plusButton;

}else{

return [super hitTest:point withEvent:event];

}

}else {

return [super hitTest:point withEvent:event];

}

}

//被点击的方法

- (void)plusClick

{

// 通知代理

if ([self.tabBarDelegate respondsToSelector:@selector(tabBarDidClickPlusButton:)]) {

[self.tabBarDelegate tabBarDidClickPlusButton:self];

}

}

2、tabBar是UITabBarController的只读成员变量（属性），是不让修改的，在UITabBarController.m中的操作如下：

@interface WXTabbarViewController ()<UITabBarDelegate>

@end

3、然后在UITabBarController.m初始化里面我们可以使用KVC的方式，更换系统自带的UITabBar，实现代码如下：

xxxTabBar（自定义的tabbar） *tabBar = [[xxxTabBar alloc] init]; 

xxxTabBar.tabBarDelegate= self;

[self setValue:tabBar forKeyPath:@"tabBar"];

4、在UITabBarController.m实现点击的代理方法

- (void)tabBarDidClickPlusButton:(WXReleaseTabBar *)tabBar

{

NSLog(@"发布按钮");

//    ComposeViewController *composeViewController= [[ComposeViewController alloc] init];

//    UINavigationController * navigationController = [[UINavigationController alloc]initWithRootViewController:composeViewController];

//    [self presentViewController:navigationController animated:YES completion:nil];

}