ViewController.h
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
@property (weak, nonatomic) IBOutlet UILabel *lab1;
@property (weak, nonatomic) IBOutlet UILabel *lab2;
@property (weak, nonatomic) IBOutlet UILabel *lab3;
@property (weak, nonatomic) IBOutlet UILabel *lab4;
@end
ViewController.m
#import "ViewController.h"
@interface ViewController ()
//创建定时器(因为下面两个方法都使用,所以定时器拿出来设置为一个属性)
@property(nonatomic,strong)NSTimer * countDownTimer;//定时器
@property(nonatomic,strong)NSString *timerservice;//服务器保留时间
@property(nonatomic,strong)NSString *timetoday;//当前时间
@end
@implementation ViewController
static NSInteger secondsCountDown ; //倒计时总的秒数
-(void) viewDidLoad {
[super viewDidLoad];
self.timetoday = [self getCurrentTimes];//获取当前时间
self.timerservice = @"17:40:00";//预设一个服务器记录的时间
self.lab1.text = [NSString stringWithFormat:@"当前时间 %@" ,self.timetoday ];//当前时间
self.lab2.text = [NSString stringWithFormat:@"服务器保留时间 %@",self.timerservice];//服务器保留时间
[self pleaseInsertStarTimeo:self.timerservice andInsertEndTime:self.timetoday];
}
#pragma mark 获取当前时间
-(NSString*)getCurrentTimes{
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
//设置你想要的格式,hh与HH的区别:分别表示12小时制,24小时制
[formatter setDateFormat:@"HH:mm:ss"];
//现在时间,你可以输出来看下是什么格式
NSDate *datenow = [NSDate date];
//将nsdate按formatter格式转成nsstring
NSString *currentTimeString = [formatter stringFromDate:datenow];
NSLog(@"currentTimeString = %@",currentTimeString);
return currentTimeString;
}
#pragma mark 开始倒计时
-(IBAction)click:(UIButton *)sender {
_countDownTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(countDownAction) userInfo:nil repeats:YES];
}
#pragma 计算2个时间差
-(void )pleaseInsertStarTimeo:(NSString *)time1 andInsertEndTime:(NSString *)time2{
// 1.将时间转换为date
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"HH:mm:ss";
NSDate *date1 = [formatter dateFromString:time1];
NSDate *date2 = [formatter dateFromString:time2];
// 2.创建日历
NSCalendar *calendar = [NSCalendar currentCalendar];
NSCalendarUnit type = NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
// 3.利用日历对象比较两个时间的差值
NSDateComponents *cmps = [calendar components:type fromDate:date1 toDate:date2 options:0];
// 4.输出结果
NSLog(@"两个时间相差%ld小时%ld分钟%ld秒",cmps.hour, cmps.minute, cmps.second);
self.lab3.text =[NSString stringWithFormat:@"两个时间相差%02ld小时%02ld分钟%02ld秒",cmps.hour, cmps.minute, cmps.second];
secondsCountDown = cmps.hour*3600+cmps.minute*60+cmps.second;//给倒计时总的秒数赋值
self.lab4.text = [NSString stringWithFormat:@"%02ld:%02ld:%02ld",cmps.hour, cmps.minute, cmps.second];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
#pragma mark 实现倒计时动作
-(void)countDownAction{
//倒计时-1
secondsCountDown--;
//重新计算 时/分/秒
NSString *str_hour = [NSString stringWithFormat:@"%02ld",secondsCountDown/3600];
NSString *str_minute = [NSString stringWithFormat:@"%02ld",(secondsCountDown%3600)/60];
NSString *str_second = [NSString stringWithFormat:@"%02ld",secondsCountDown%60];
//修改倒计时标签及显示内容
self.lab4.text = [NSString stringWithFormat:@"%@:%@:%@",str_hour,str_minute,str_second];
//当倒计时到0时做需要的操作，比如验证码过期不能提交
if(secondsCountDown==0){
[_countDownTimer invalidate];
}
}
@end
image.png
