今天博主有一个倒计时效果的实现的需求,遇到了一些困难点,在此和大家分享,希望能够共同进步.
首先在需要用到的地方解析总的倒计时时间,博主没有封装,各位看官可以自行封装
#pragma mark--------新修改,增加倒计时
NSString *stringOfTime=[NSString stringWithFormat:@"%@",d[@"shipping_time"]];
double endUnixTime = [stringOfTime doubleValue];
// NSLog(@"++++++%.2f",endUnixTime);
NSCalendar *cal = [NSCalendar currentCalendar];
unsigned int unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
NSDate *date1 = [NSDate date];
NSDate *date2 = [NSDate dateWithTimeIntervalSince1970:endUnixTime];
NSDateComponents *dOfd = [cal components:unitFlags fromDate:date1 toDate:date2 options:0];
NSInteger sec = [dOfd hour]*3600+[dOfd minute]*60+[dOfd second];
//sec是总秒数
// NSLog(@"**********%@",dOfd);
UILabel *labelOfTime=(UILabel *)[_scroll viewWithTag:6954321];
if (sec>0) {
[self setCountDownWithTotalSec:sec withLabel:labelOfTime];
}
然后使用GCD实现倒计时功能
- (void)setCountDownWithTotalSec:(NSInteger)totalSec withLabel:(UILabel *)timeLbl{
__block NSInteger timeout = totalSec; //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
timeLbl.text = @"00:00:00";
});
}else{
long hours = timeout / 3600;
long minutes = (timeout - hours * 3600) / 60;
int seconds = timeout % 60;
NSString *strTime = [NSString stringWithFormat:@"%.2ld%.2ld%.2d",hours,minutes, seconds];
NSString *firstH = [strTime substringWithRange:NSMakeRange(0, 1)];
NSString *secondH = [strTime substringWithRange:NSMakeRange(1, 1)];
NSString *firstM = [strTime substringWithRange:NSMakeRange(2, 1)];
NSString *secondM = [strTime substringWithRange:NSMakeRange(3, 1)];
NSString *firstS = [strTime substringWithRange:NSMakeRange(4, 1)];
NSString *secondS = [strTime substringWithRange:NSMakeRange(5, 1)];
NSString *newTimeString = [NSString stringWithFormat:@"%@%@:%@%@:%@%@",firstH,secondH,firstM,secondM,firstS,secondS];
dispatch_async(dispatch_get_main_queue(), ^{
timeLbl.text = newTimeString;//回到主线程显示
});
timeout--;
}
});
dispatch_resume(_timer);
}
上述定时方法在进入后台,挂起,返回前台后,会产生调表,因为两个定时器都在计时,可以在回调中判断程序状态,取消定时
dispatch_source_set_event_handler(_timer, ^{
if ([UIApplication sharedApplication].applicationState==UIApplicationStateBackground) {
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
timeLbl.text = @" ";
});
}