NStimer 倒计时实现

来源：互联网发布：河南郑州网络诈骗6.29 编辑：程序博客网时间：2024/06/17 12:21

1、思路：当点击UIswich控件的开启功能时，再开始执行一个倒计时功能的实现，关闭了UIswich控件，则不再执行倒计时功能。

2、代码实现:

////  ViewController.m//  NStimer////  Created by rimi on 15/11/11.//  Copyright © 2015年 Liu. All rights reserved.//#import "ViewController.h"@interface ViewController (){    int secondsCountDown;//倒计时总时长    NSTimer *countDownTimer;//计时器    UILabel *labelText;//显示秒数}@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    labelText = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 120, 30)];    [self.view addSubview:labelText];        UISwitch *theSwitch = [[UISwitch alloc] initWithFrame:CGRectMake(100, 300, 120, 30)];    [theSwitch addTarget:self                  action:@selector(switchToChange:)        forControlEvents:UIControlEventValueChanged];    [self.view addSubview:theSwitch];        secondsCountDown = 10;//设置秒数}- (void)timeFireMethod{    //倒计时减1    secondsCountDown--;    //修改倒计时便签显示内容    labelText.text = [NSString stringWithFormat:@"%d",secondsCountDown];    //当倒计时到0时，打印倒倒计时结束    if (secondsCountDown == 0) {        [countDownTimer invalidate];/**< 时间无效  */         [labelText removeFromSuperview];/**< 移除显示  */                UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"温馨提示"                                                                       message:@"您应该记账了！"                                                                       preferredStyle:UIAlertControllerStyleAlert];        UIAlertAction    *action = [UIAlertAction                                 actionWithTitle:@"确定"                                           style:UIAlertActionStyleDefault                                         handler:nil];        [alert addAction:action];        [self presentViewController:alert animated:YES completion:nil];        //        NSLog(@"倒计时结束");    }}//监听UISwitch事件- (void)switchToChange:(UISwitch*)sender{        if (sender.isOn) {                countDownTimer = [NSTimer scheduledTimerWithTimeInterval:1                                                          target:self                                                          selector:@selector(timeFireMethod)                                                          userInfo:nil                                                          repeats:YES];        labelText.text = [NSString stringWithFormat:@"%d",secondsCountDown];        secondsCountDown = 10;        [self timeFireMethod];        [self.view addSubview:labelText];    }    else    {        [countDownTimer invalidate];        [labelText removeFromSuperview];        NSLog(@"已关闭计时");    }}@end

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