自定义的UITabbar上面的按钮的x坐标的计算方法

 for (int i = ; i < 4; i++) {//4是按钮的个数
        NSString *backImage = backgroud[i];
        NSString *heightImage = heightBackground[i];

        UIButton *button = [UIFactory createButton:backImage highlighted:heightImage];
        button.showsTouchWhenHighlighted = YES;
        button.frame = CGRectMake(/  * i + , (-)/, , );//4是按钮的个数;25是自己不断修改得来的.
        [button addTarget:self action:@selector(selectedTab:) forControlEvents:UIControlEventTouchUpInside];
        [_tabbarView addSubview:button];
    }

效果如图：