#pragma mark - Countdown algorithm
- (void)setUpTimer {
self.timeLeft = 15;
//設置resend按鈕爲隱藏，倒計時label爲顯示，這種倒計時最好是不要用button做顯示，不好看，效果也不明顯，具體我給忘了。因爲本來是想直接就用button的，就是title顯示不同，結果證明不行
[self.resendVerifyCodeButton setHidden:YES];
[self.sendEmailCountTimeLabel setHidden:NO];
[self.sendEmailCountTimeLabel setAlpha:0.5f];//保證半失焦的狀態，灰暗
[self reloadCountdownLabel];
[self.countdownTimer invalidate];
self.countdownTimer = nil;
self.countdownTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(countDown:) userInfo:nil repeats:YES];
}
- (void)reloadCountdownLabel {
//倒計時過程中顯示的文本
if (self.timeLeft >= 0) {
[self.sendEmailCountTimeLabel setText:[NSString stringWithFormat:@"Resend verification email\n (After %i seconds)",self.timeLeft]];
}
else {
[self.sendEmailCountTimeLabel setText:[NSString stringWithFormat:@"Resend verification email\n (After %i seconds)",0]];
}
}
- (void)countDown:(NSTimer *)timer {
self.timeLeft--;
[self reloadCountdownLabel];
if (self.timeLeft == -1) {
[self.countdownTimer invalidate];
self.countdownTimer = nil;
//倒計時結束的UI：
[self.resendVerifyCodeButton setHidden:NO];
[self.sendEmailCountTimeLabel setHidden:YES];
}
}
使用方式比較簡單啦：
點擊完resend button，call SMS api成功之後，就可以開始倒計時了。這裏就不多寫了
- (IBAction)resendVerifyCodeAction:(id)sender {
[self setUpTimer];
}