ios 簡單的倒計時驗證碼數秒過程實現

 timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timerFireMethod:) userInfo:nil repeats:YES];

//倒計時方法驗證碼實現倒計時60秒，60秒後按鈕變換開始的樣子-(void)timerFireMethod:(NSTimer *)theTimer {    if (seconds == 1) {        [theTimer invalidate];        seconds = 60;        [validCodeBtn_ setTitle:@"擷取驗證碼" forState: UIControlStateNormal];        [validCodeBtn_ setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];        [validCodeBtn_ setEnabled:YES];    }else{        seconds--;        NSString *title = [NSString stringWithFormat:MSG_DYNAMIC_CODE_WAIT,seconds];        [validCodeBtn_ setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];        [validCodeBtn_ setEnabled:NO];        [validCodeBtn_ setTitle:title forState:UIControlStateNormal];    }}//如果登陸成功，停止驗證碼的倒數，- (void)releaseTImer {    if (timer) {        if ([timer respondsToSelector:@selector(isValid)]) {            if ([timer isValid]) {                [timer invalidate];                seconds = 60;            }        }    }}