·您现在的位置： 云翼网络 >> 文章中心 >> 网站建设 >> app软件开发 >> IOS开发 >> 使用GCD实现倒计时效果

【如有意向点此提交需求】关于我们

使用GCD实现倒计时效果

作者：佚名      IOS开发编辑：admin      更新时间：2022-07-23

效果如下：

ViewController.h

1 #import <UIKit/UIKit.h>
2 
3 @interface ViewController : UIViewController
4 @PRoperty (assign, nonatomic) NSInteger surplusSecond;
5 
6 @property (strong, nonatomic) IBOutlet UILabel *lblMessage;
7 @property (strong, nonatomic) IBOutlet UIButton *btnSendCAPTCHA;
8 
9 @end

ViewController.m

 1 #import "ViewController.h"
 2 
 3 @interface ViewController ()
 4 - (void)layoutUI;
 5 - (void)countDown;
 6 @end
 7 
 8 @implementation ViewController
 9 #define kSurplusSecond 5
10 
11 - (void)viewDidLoad {
12     [super viewDidLoad];
13     
14     [self layoutUI];
15 }
16 
17 - (void)didReceiveMemoryWarning {
18     [super didReceiveMemoryWarning];
19     // Dispose of any resources that can be recreated.
20 }
21 
22 - (void)layoutUI {
23     _surplusSecond = kSurplusSecond; //剩余秒数；这里指验证码发送完，间隔多少秒才能再次点击「验证」按钮进行发送验证码
24     
25     _btnSendCAPTCHA.tintColor = [UIColor darkGrayColor];
26     _btnSendCAPTCHA.layer.masksToBounds = YES;
27     _btnSendCAPTCHA.layer.cornerRadius = 10.0;
28     _btnSendCAPTCHA.layer.borderColor = [UIColor grayColor].CGColor;
29     _btnSendCAPTCHA.layer.borderWidth = 1.0;
30 }
31 
32 /**
33  *  倒计时
34  */
35 - (void)countDown {
36     //全局并发队列
37     dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
38     //主队列；属于串行队列
39     dispatch_queue_t mainQueue = dispatch_get_main_queue();
40     
41     //定时循环执行事件
42     //dispatch_source_set_timer 方法值得一提的是最后一个参数（leeway），他告诉系统我们需要计时器触发的精准程度。所有的计时器都不会保证100%精准，这个参数用来告诉系统你希望系统保证精准的努力程度。如果你希望一个计时器每5秒触发一次，并且越准越好，那么你传递0为参数。另外，如果是一个周期性任务，比如检查email，那么你会希望每10分钟检查一次，但是不用那么精准。所以你可以传入60，告诉系统60秒的误差是可接受的。他的意义在于降低资源消耗。
43     dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, globalQueue);
44     dispatch_source_set_timer(timer, DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC, 0.0 * NSEC_PER_SEC);
45     dispatch_source_set_event_handler(timer, ^{ //计时器事件处理器
46         NSLog(@"Event Handler");
47         if (_surplusSecond <= 0) {
48             dispatch_source_cancel(timer); //取消定时循环计时器；使得句柄被调用，即事件被执行
49             dispatch_async(mainQueue, ^{
50                 _btnSendCAPTCHA.enabled = YES;
51                 [_btnSendCAPTCHA setTitle:@"验证" forState:UIControlStateNormal];
52                 
53                 _lblMessage.text = @"使用 GCD 实现倒计时效果";
54                 _surplusSecond = kSurplusSecond;
55             });
56         } else {
57             _surplusSecond--;
58             dispatch_async(mainQueue, ^{
59                 NSString *btnInfo = [NSString stringWithFormat:@"%ld秒", (long)(_surplusSecond + 1)];
60                 _btnSendCAPTCHA.enabled = NO;
61                 [_btnSendCAPTCHA setTitle:btnInfo forState:UIControlStateDisabled];
62             });
63         }
64     });
65     dispatch_source_set_cancel_handler(timer, ^{ //计时器取消处理器；调用 dispatch_source_cancel 时执行
66         NSLog(@"Cancel Handler");
67     });
68     dispatch_resume(timer);  //恢复定时循环计时器；Dispatch Source 创建完后默认状态是挂起的，需要主动恢复，否则事件不会被传递，也不会被执行
69 }
70 
71 - (IBAction)sendCAPTCHA:(id)sender {
72     _lblMessage.text = [NSString stringWithFormat:@"验证码发送成功，%d秒后可重新发送", kSurplusSecond];
73     
74     [self countDown];
75 }
76 
77 @end

Main.storyboard

 

 1 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 2 <document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="7706" systemVersion="14E46" targetRuntime="iOS.CocoaTouch" propertyaccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="vXZ-lx-hvc">
 3     <dependencies>
 4         <deployment identifier="iOS"/>
 5         <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="7703"/>
 6     </dependencies>
 7     <scenes>
 8         <!--View Controller-->
 9         <scene sceneID="ufC-wZ-h7g">
10             <objects>
11                 <viewController id="vXZ-lx-hvc" customClass="ViewController" sceneMemberID="viewController">
12                     <layoutGuides>
13                         <viewControllerLayoutGuide type="top" id="jyV-Pf-zRb"/>
14                         <viewControllerLayoutGuide type="bottom" id="2fi-mo-0CV"/>
15                     </layoutGuides>
16                     <view key="view" contentMode="scaleToFill" id="kh9-bI-dsS">
17                         <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
18                         <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
19                         <subviews>
20                             <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="使用 GCD 实现倒计时效果" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="1Kh-pV-cfz">
21                                 <rect key="frame" x="200" y="289.5" width="200" height="20.5"/>
22                                 <fontDescription key="fontDescription" type="system" pointSize="17"/>
23                                 <color key="textColor" cocoaTouchSystemColor="darkTextColor"/>
24                                 <nil key="highlightedColor"/>
25                             </label>
26                             <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="rFe-Xb-ZSc">
27                                 <rect key="frame" x="240" y="510" width="120" height="50"/>
28                                 <constraints>
29                                     <constraint firstAttribute="width" constant="120" id="gVH-aT-gen"/>
30                                     <constraint firstAttribute="height" constant="50" id="jJP-Vc-fpy"/>
31                                 </constraints>
32                                 <state key="normal" title="验证">
33                                     <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
34                                 </state>
35                                 <connections>
36                                     <action selector="sendCAPTCHA:" destination="vXZ-lx-hvc" eventType="touchUpInside" id="I6T-s9-9H6"/>
37                                 </connections>
38                             </button>
39                         </subviews>
40                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
41                         <constraints>
42                             <constraint firstAttribute="centerX" secondItem="rFe-Xb-ZSc" secondAttribute="centerX" id="CoE-CP-eDN"/>
43                             <constraint firstAttribute="centerY" secondItem="1Kh-pV-cfz" secondAttribute="centerY" id="bX4-jS-0xm"/>
44                             <constraint firstAttribute="centerX" secondItem="1Kh-pV-cfz" secondAttribute="centerX" id="mKH-Zw-Utb"/>
45                             <constraint firstItem="2fi-mo-0CV" firstAttribute="top" secondItem="rFe-Xb-ZSc" secondAttribute="bottom" constant="40" id="y3Q-IA-qIO"/>
46                         </constraints>
47                     </view>
48                     <connections>
49                         <outlet property="btnSendCAPTCHA" destination="rFe-Xb-ZSc" id="UFG-TS-ImX"/>
50                         <outlet property="lblMessage" destination="1Kh-pV-cfz" id="gzx-3T-euc"/>
51                     </connections>
52                 </viewController>
53                 <placeholder placeholderIdentifier="IBFirstResponder" id="x5A-6p-PRh" sceneMemberID="firstResponder"/>
54             </objects>
55         </scene>
56     </scenes>
57 </document>

输出结果：

1 2015-08-31 14:40:02.083 KMCountDown[5102:103949] Event Handler
2 2015-08-31 14:40:03.087 KMCountDown[5102:103949] Event Handler
3 2015-08-31 14:40:04.084 KMCountDown[5102:103949] Event Handler
4 2015-08-31 14:40:05.086 KMCountDown[5102:103971] Event Handler
5 2015-08-31 14:40:06.085 KMCountDown[5102:103949] Event Handler
6 2015-08-31 14:40:07.085 KMCountDown[5102:103949] Event Handler
7 2015-08-31 14:40:07.085 KMCountDown[5102:103949] Cancel Handler