新浪微博加号按钮OC代码

#import "WBTabBar.h"@interface WBTabBar()/// 加号按钮@property(nonatomic,weak) UIButton *plusBtn;@end@implementation WBTabBar-(instancetype)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if(self){        // 添加一个+号按钮 到tabbar中        UIButton *plusBtn = [[UIButton alloc] init];        // 设置背景        [plusBtn setBackgroundImage:[UIImage imageNamed:@"tabbar_compose_button"] forState:UIControlStateNormal];        [plusBtn setBackgroundImage:[UIImage imageNamed:@"tabbar_compose_button_highlighted"] forState:UIControlStateHighlighted];        // 增加+号图片        [plusBtn setImage:[UIImage imageNamed:@"tabbar_compose_icon_add"] forState:UIControlStateNormal];        [plusBtn setImage:[UIImage imageNamed:@"tabbar_compose_icon_add_highlighted"] forState:UIControlStateHighlighted];        // 大小        [plusBtn sizeToFit];        // 监听事件        [plusBtn addTarget:self action:@selector(plusClick) forControlEvents:UIControlEventTouchUpInside];        [self addSubview:plusBtn];        self.plusBtn = plusBtn;    }    return self;}// 加号按钮点击事件- (void)plusClick{    NSLog(@"加号按钮被点击了");}// 标签按钮布局- (void)layoutSubviews{    [ super layoutSubviews ]; // 加号按钮居中显示   self.plusBtn.translatesAutoresizingMaskIntoConstraints = false;    //水平居中    NSLayoutConstraint *plusBtn_CenterX = [self.plusBtn.centerXAnchor constraintEqualToAnchor:self.centerXAnchor];    //垂直居中    NSLayoutConstraint *plusBtn_CenterY = [self.plusBtn.centerYAnchor constraintEqualToAnchor:self.centerYAnchor];    //宽度约束    NSLayoutConstraint *plusBtn_Width = [self.plusBtn.widthAnchor constraintEqualToConstant:64];    //高度约束    NSLayoutConstraint *plusBtn_Height = [self.plusBtn.heightAnchor constraintEqualToConstant:44];    [NSLayoutConstraint activateConstraints:@[plusBtn_CenterX,plusBtn_CenterY,plusBtn_Width,plusBtn_Height]];    } /// 其他按钮尺寸及位置    // 按钮索引    CGFloat index = 0;    // 按钮宽度    CGFloat itemW = self.bounds.size.width / 5;    CGFloat itemH = self.bounds.size.height;    for (UIView * subView in self.subviews) {        if ([subView isKindOfClass:NSClassFromString(@"UITabBarButton")]) {            // 设置宽度            subView.frame = CGRectMake(itemW * index, 0, itemW, itemH);            index += 1;            if (index == 2) {                index += 1;            }        }    }