iOS开发-使用GCD机制来实现倒计时功能

使用GCD机制来实现倒计时功能。实现的是类似注册页面发送验证码的倒计时。

- (void)getCodeSuccess

{

__block int timeout=60; //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

[_BTN_code setBackgroundImage:[UIImage imageNamed:@"send_yanzhengma"] forState:UIControlStateNormal];

[_BTN_code setTitle:@"发送验证码" forState:UIControlStateNormal];

_BTN_code.userInteractionEnabled = YES;

});

}else{

// int minutes = timeout / 60;

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(@"____%@秒",strTime);

[_BTN_code setBackgroundImage:[UIImage imageNamed:@"send_yanzhengma"] forState:UIControlStateNormal];

[_BTN_code setTitle:[NSString stringWithFormat:@"%@秒后重新发送",strTime] forState:UIControlStateNormal];

_BTN_code.userInteractionEnabled = NO;

});

timeout--;

}

});

dispatch_resume(_timer);

}