在TabBar基础上,在中间的位置加上一个Button,重新设置布局

custom_tabBar.png

新建一个类,继承自TabBar

OC:

#import "JSTabBar.h"
#import "Masonry.h"

@interface JSTabBar ()
@property (nonatomic,strong) UIButton *composeButton;
@end

@implementation JSTabBar

- (instancetype)init{
    self = [super init];
    if (self) {
     
        //设置UI
        [self setUI];
        
    }
    
    return self;
}

- (void)setUI{
    
    [self addSubview:self.composeButton];
    [self.composeButton mas_makeConstraints:^(MASConstraintMaker *make) {
        make.center.mas_equalTo(self);
    }];
    
}

- (void)layoutSubviews{
    [super layoutSubviews];
    
    CGFloat width = [UIScreen mainScreen].bounds.size.width / 5;
    CGFloat index = 0;
    
    for (UIView *view in self.subviews) {
        
        if ([view isKindOfClass:NSClassFromString(@"UITabBarButton")]) {
            
            CGRect frame = view.frame;
            frame.size.width = width;
            frame.origin.x = index * width;
            view.frame = frame;
            
            index ++;
            
            if (index == 2) {
                index ++;
            }
            
        }
    }

}

//按钮点击事件中调用代理方法
- (void)buttonClick:(UIButton *)sender{
    
    if ([self.tabBarDelegate respondsToSelector:@selector(tabBarDelegateWithTabBar:)]) {
        [self.tabBarDelegate tabBarDelegateWithTabBar:self];
    }
}

/**
 *  ComposeButton懒加载
 *
 *  @return composeButton
 */
- (UIButton *)composeButton{
    
    if (_composeButton == nil) {
        _composeButton = [[UIButton alloc]init];
        [_composeButton setBackgroundImage:[UIImage imageNamed:@"tabbar_compose_button"] forState:UIControlStateNormal];
        [_composeButton setBackgroundImage:[UIImage imageNamed:@"tabbar_compose_button_highlighted"] forState:UIControlStateHighlighted];
        [_composeButton setImage:[UIImage imageNamed:@"tabbar_compose_icon_add"] forState:UIControlStateNormal];
        [_composeButton setImage:[UIImage imageNamed:@"tabbar_compose_icon_add_highlighted"] forState:UIControlStateHighlighted];
        [_composeButton sizeToFit];
        [_composeButton addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
    }
    return _composeButton;
}

@end

自定义的TabBar样式完成,但此时还无法Push控制器,所以需要通过代理的方式,设置代理对象,进行Push操作

#import <UIKit/UIKit.h>

@class JSTabBar;
//声明协议
@protocol JSTabBarDelegate <NSObject>

@optional
//声明代理方法
- (void)tabBarDelegateWithTabBar:(JSTabBar *)tabBar;

@end

@interface JSTabBar : UITabBar
//声明代理对象
@property (nonatomic,weak) id tabBarDelegate;
@end

Swift:

// MARK - 声明协议
protocol JSTabBarDelegate : NSObjectProtocol {
    
    func tabBarComposeButtonClick()
}

class JSTabBar: UITabBar {
    
    //声明代理对象
    weak var tabBarDelegate:JSTabBarDelegate?

    private lazy var composeButton: UIButton = {
        let btn = UIButton()
        btn.setImage(UIImage(named: "tabbar_compose_icon_add"), forState: UIControlState.Normal)
        btn.setImage(UIImage(named: "tabbar_compose_icon_add_highlighted"), forState: UIControlState.Highlighted)
        btn.setBackgroundImage(UIImage(named: "tabbar_compose_button"), forState: UIControlState.Normal)
        btn.setBackgroundImage(UIImage(named: "tabbar_compose_button_highlighted"), forState: UIControlState.Highlighted)
        btn.sizeToFit()
        return btn
        
    }()
    
    @objc private func composeButtonClick() -> Void {
        
        //代理对象执行代理方法
        tabBarDelegate?.tabBarComposeButtonClick()
    }
    
    // MARK: -添加button
    func setupUI() -> Void {
        addSubview(composeButton)
    }
    
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        setupUI() //添加中间按钮
        composeButton.addTarget(self, action: #selector(composeButtonClick), forControlEvents: UIControlEvents.TouchUpInside)
        
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        //设置中间按钮的Frame
        composeButton.center.x = frame.size.width * 0.5
        composeButton.center.y = frame.size.height * 0.5
        
        //调整TabBar上button的Frame NSClassFromString("UITabBarButton")
        var index: CGFloat = 0
        let width: CGFloat = frame.width / 5
        for value in subviews {
            
            if value.isKindOfClass(NSClassFromString("UITabBarButton")!)  {
                
                value.frame.size.width = width
                value.frame.origin.x = index * width
                
                index++
                
                if index == 2 {
                    
                    index++
                }
                
            }
        }
    }
    
    
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    

}

这样自定义的TabBar就完成了,在使用上需要注意:
因为UITabBarController的tabBar为只读属性,所以无法按照正常方式设置,这里就需要通过KVC设置只读属性

在ViewDidLoad中

OC:

    JSTabBar *tabBar = [[JSTabBar alloc]init];
    tabBar.tabBarDelegate = self;
    [self setValue:tabBar forKey:@"tabBar"];

Swift:

   let tabBar = JSTabBar()
   tabBar.tabBarDelegate = self
   setValue(tabBar, forKey: "tabBar")

补充:
1.在OC中不能像Swift那样直接设置frame属性,需要借助中间变量
2.tabBar为只读属性,需要借助KVC设置
3.自定义布局完成后,还需要通过代理或者Block/闭包的方式委托控制器实现Push操作
4.Swift下重写了init(frame: CGRect)方法,就不再支持xib和StoryBoard的方式,如果需要用到xib或storyBoard,需要自定义方法来创建TabBar