iOS Development--Verification code

The first step , drag two space textfiled and button to storyboard on the Viewcontroller.

The second step, drag lines, link to the code in the. h file is as follows:

1	@property (weak, nonatomic) IBOutlet UIButton *l_timeButton;

The third step is to set the listener in the M file for L_timebutton and listen for click events.

1234	- (void)viewDidLoad {    [super viewDidLoad];    [_l_timeButton addTarget:self action:@selector(startTime) forControlEvents:UIControlEventTouchUpInside];}

Fourth Step, in the method "StartTime" to achieve the countdown function

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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);}

A Verification code countdown function is written.

iOS Development--Verification code