进入App弹出提示框

1 ，声明变量    

/* 遮罩window */

@property(nonatomic,strong)UIWindow *coverWindow;

/* 弹框 */

@property(nonatomic,strong)UIView *alertView;

/* 弹框按钮 */

@property(nonatomic,strong)UIButton *nextBtn;

/* 弹框标题 */

@property(nonatomic,strong)UILabel *titleLab;

//kUIScreenHeight  屏幕高度

2 ， 根据字数设置高度

#pragma mark 弹出公告提示

-(UIView *)alertView

{

NSString *textStr = @"系统将于2017年4月20日17~19点间进行升级，在升级期间系统将停止使用，请你提前处理系统中待处理任务。";

    if (!_alertView) {

        CGRect rect = [textStr boundingRectWithSize:CGSizeMake(kUIScreenWidth -100, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont fontWithName:kPingFang_Regular size:14]} context:nil];

        

        float alertHight = rect.size.height + 55 +85;

//高度小于230   就固定高度为230 

//高度大于   屏幕的高度-130  固定高度 屏幕高度-130

        if (alertHight <= 230) {

            alertHight = 230;

        } else if (alertHight >= kUIScreenHeight-130) {

            alertHight = kUIScreenHeight-130;

        }else {

            alertHight = rect.size.height +40+ 40 +15 +70+15;

        }

        _alertView = [[UIView alloc]initWithFrame:CGRectMake(30, (kUIScreenHeight-alertHight)/2, kUIScreenWidth-60, alertHight)];

        _alertView.backgroundColor = [UIColor whiteColor];

        _coverWindow = [[UIWindow alloc]initWithFrame:CGRectMake(0, 0, kUIScreenWidth, kUIScreenHeight)];

        _coverWindow.backgroundColor = [UIColor colorWithWhite:0 alpha:0.4];

        

        _alertView.clipsToBounds = YES;

        _alertView.layer.cornerRadius = 4;

        [_coverWindow addSubview:_alertView];

        _coverWindow.windowLevel = UIWindowLevelNormal;

        _coverWindow.hidden = YES;

        [[UIApplication sharedApplication].keyWindow addSubview:_coverWindow];

        //右上角 X 按钮

        UIButton *deleteBtn = [UIButton buttonWithType:UIButtonTypeCustom];

        deleteBtn.backgroundColor = [CommonFunctions colorWithHex:0xffffff];

        [deleteBtn setFrame:CGRectMake(_alertView.frame.size.width-31, 15, 16, 16)];

        [deleteBtn setBackgroundImage:[UIImage imageNamed:@"btn_cls"] forState:UIControlStateNormal];

        [deleteBtn addTarget:self action:@selector(deleteBtnClick:) forControlEvents:UIControlEventTouchUpInside];

        [_alertView addSubview:deleteBtn];

        

        //下一步的按钮

        UIButton *nextBtn = [UIButton buttonWithType:UIButtonTypeCustom];

        nextBtn.backgroundColor = [CommonFunctions colorWithHex:0x11a1b4];

        [nextBtn setFrame:CGRectMake(30, _alertView.frame.size.height-70, _alertView.frame.size.width-60, 40)];

        [nextBtn setTitle:buttonText forState:UIControlStateNormal];

        [nextBtn.titleLabel setFont:[UIFont fontWithName:kPingFang_Regular size:16]];

        [nextBtn addTarget:self action:@selector(nextBtnClick:) forControlEvents:UIControlEventTouchUpInside];

        [_alertView addSubview:nextBtn];

        

        //标题 Lab

        UILabel *titleLab = [[UILabel alloc]initWithFrame:CGRectMake(10, 20, _alertView.frame.size.width-20, 20)];

        titleLab.text = titleStr;

        titleLab.textColor = [CommonFunctions colorWithHex:0x666666];

        titleLab.font = [UIFont fontWithName:kPingFang_Regular size:16];

        titleLab.textAlignment = NSTextAlignmentCenter;

        [_alertView addSubview:titleLab];

        

        //显示内容的textView （也可以用lab）

        UITextView *textView = [[UITextView alloc]initWithFrame:CGRectMake(20, 40+15, _alertView.frame.size.width-40, alertHight-40-15-70-15)];

        textView.text = textStr;

        textView.textColor = [CommonFunctions colorWithHex:0x999999];

        textView.font = [UIFont fontWithName:kPingFang_Regular size:14];

        textView.editable = NO;

        textView.bounces = NO;

        [_alertView addSubview:textView];

    }

    return _alertView;

}

3 ， 调用   显示和隐藏

　　　　　　//显示

　　　　　　[self alertView];

                  self.alertView.hidden = NO;

                  self.coverWindow.hidden = NO;

 　　　　　　//隐藏　

 　　　　　　self.alertView.hidden = YES;

    　　　　　self.coverWindow.hidden = YES;

4 ，实现按钮的方法 就OK了