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第一步,拖两个空间textfiled和button到storyboard上的viewcontroller上。
第二步,拖线,链接到.h文件中代码如下:
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@property (weak, nonatomic) IBOutlet UIButton *l_timeButton; |
第三步,在,m文件中为l_timeButton设置监听器,监听点击事件。
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- ( void )viewDidLoad { [super viewDidLoad]; [_l_timeButton addTarget:self action:@selector(startTime) forControlEvents:UIControlEventTouchUpInside]; } |
第四步,在方法“startTime”中实现倒计时功能
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-( void )startTime{ __block int timeout=30; //倒计时时间 dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue); dispatch_source_set_timer(_timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行 dispatch_source_set_event_handler(_timer, ^{ if (timeout<=0){ //倒计时结束,关闭 dispatch_source_cancel(_timer); dispatch_async(dispatch_get_main_queue(), ^{ //设置界面的按钮显示 根据自己需求设置 [_l_timeButton setTitle:@ "发送验证码" forState:UIControlStateNormal]; _l_timeButton.userInteractionEnabled = YES; }); } else { int seconds = timeout % 60; NSString *strTime = [NSString stringWithFormat:@ "%.2d" , seconds]; dispatch_async(dispatch_get_main_queue(), ^{ //设置界面的按钮显示 根据自己需求设置 //NSLog(@"____%@",strTime); [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1]; [_l_timeButton setTitle:[NSString stringWithFormat:@ "%@秒后重新发送" ,strTime] forState:UIControlStateNormal]; [UIView commitAnimations]; _l_timeButton.userInteractionEnabled = NO; }); timeout--; } }); dispatch_resume(_timer); } |
一个验证码倒计时的功能就写好了
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原文地址:http://www.cnblogs.com/wanghuaijun/p/5260786.html