短信驗證碼倒計時的實現
在開發中,經常在需要用戶註冊的時候會需要實現驗證碼倒計時的功能,下面是解決這個問題的兩種思路(使用UIButton控件)
一、利用NSTimer計時器
1.新建一個UIButton按鈕,設置成屬性,名爲codeButton。(UIButton樣式一定要爲自定義,否則後面倒計時數秒時會出現閃爍現象)
2.定義一個NSTimer的屬性,名爲timer,同時定義一個用於計時的int變量time,設置初始值爲60。
//啓動一個定時器
self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(operatePerSecond) userInfo:nil repeats:YES];
//實現定時器中的方法
- (void)operatePerSecond {
if (time == 1) {
[self.timer invalidate];
time = 60;
[self.codeButton setTitle:@"重新獲取" forState:UIControlStateNormal];
self.codeButton.tintColor = [UIColor blackColor];
self.codeButton.enabled = YES;
}else {
time --;
[self.codeButton setTitle:[NSString stringWithFormat:@"%ds" ,time] forState:UIControlStateNormal];
}
}
3.此時主要邏輯已經完成,但要記得:在本頁面即將消失的時候也要停掉計時器self.timer。
二、利用GCD實現
1.定義一個用於計時的time(此時要用block修飾)--- block int time = 60;
//倒計時時間
__block int timeout = 60;
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_TIME_NOW, 1.0 * NSEC_PER_SEC, 0 * NSEC_PER_SEC);
dispatch_source_set_event_handler(timer, ^{
if(timeout == 1){
//倒計時結束,關閉
dispatch_source_cancel(timer);
dispatch_async(dispatch_get_main_queue(), ^{
timeout = 60;
[self.codeButton setTitle:@"重新獲取" forState:UIControlStateNormal];
self.codeButton.tintColor = [UIColor blackColor];
self.codeButton.enabled = YES;
});
}else{
NSString *strTime = [NSString stringWithFormat:@"%ds",timeout];
dispatch_async(dispatch_get_main_queue(), ^{
[self.codeButton setTitle:strTime forState:UIControlStateNormal];
});
timeout--;
}
});
dispatch_resume(timer);
2.把上述代碼寫入點擊方法中即可實現倒計時效果。