一 概述
本文分别介绍如何在OC和Swift中实现倒计时功能：
- OC中实现倒计时的类是NSTimer
- Swift中实现倒计时的类是Timer
二 效果图
三 代码实现
3.1 OC模式下(ViewController.m)
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| #import "ViewController.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *counterLabel;
@property (weak, nonatomic) IBOutlet UIBarButtonItem *pause;
@property (strong,nonatomic) NSTimer *timer;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
}
//开始
- (IBAction)start:(UIBarButtonItem *)sender
{
self.counterLabel.text=@"2";
self.timer=[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateTimer:) userInfo:@"hello timer" repeats:YES];
}
//暂停
- (IBAction)pause:(UIBarButtonItem *)sender
{
[self.timer invalidate];
}
-(void)updateTimer:(NSTimer *)timer
{
NSLog(@"%s",__func__);
NSLog(@"%@",timer.userInfo);
int counter=self.counterLabel.text.intValue;
if(counter<=0)
{
[self pause:self.pause];
UIAlertController *alert=[UIAlertController alertControllerWithTitle:@"开始" message:@"开始啦。。" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *sure=[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:nil];
[alert addAction:sure];
[self presentViewController:alert animated:YES completion:nil];
}else
{
self.counterLabel.text=[NSString stringWithFormat:@"%d",--counter];
}
}
@end
|
3.2 Swift模式下(ViewController.swift)
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| import UIKit
class ViewController: UIViewController {
@IBOutlet weak var counterLabel: UILabel!
@IBOutlet weak var pauseItem: UIBarButtonItem!
var timer: Timer? = nil
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
@objc func undateTimer(timer: Timer)
{
var counter:Int=Int.init(self.counterLabel.text!)!
if(counter<=0)
{
pause(self.pauseItem)
}else
{
counter-=1;
self.counterLabel.text=String.init(format: "%d",counter);
}
}
@IBAction func start(_ sender: UIBarButtonItem)
{
timer=Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(undateTimer), userInfo: "hello timer", repeats: true);
}
@IBAction func pause(_ sender: UIBarButtonItem)
{
timer?.invalidate()
}
}
|