iOS开发 | 清晰的倒计时button

这个button主要是针对获取短信验证码那一类倒计时按钮的封装。

清晰，是指逻辑清晰。

我将它的逻辑拆分成dataSource和delegate两部分：

#import <UIKit/UIKit.h>

@class CQCountdownButton;

@protocol CQCountDownButtonDataSource <NSObject>

// 设置起始倒计时秒数
- (NSInteger)startCountdownNumOfCountdownButton:(CQCountdownButton *)countdownButton;

@end

@protocol CQCountDownButtonDelegate <NSObject>

// 倒计时按钮点击时回调
- (void)countdownButtonDidClick:(CQCountdownButton *)countdownButton;
// 倒计时进行中的回调
- (void)countdownButtonDidCountdown:(CQCountdownButton *)countdownButton withRestCountdownNum:(NSInteger)restCountdownNum;
// 倒计时结束时的回调
- (void)countdownButtonDidEndCountdown:(CQCountdownButton *)countdownButton;

@end

@interface CQCountdownButton : UIButton

@property (nonatomic, weak) id <CQCountDownButtonDataSource> dataSource;
@property (nonatomic, weak) id <CQCountDownButtonDelegate> delegate;

/** 开始倒计时 */
- (void)startCountDown;
/** 释放timer */
- (void)releaseTimer;

@end

使用如下：

#import "CQCountdownButton.h"

@interface SecondViewController () <CQCountDownButtonDataSource, CQCountDownButtonDelegate>

@property (nonatomic, strong) CQCountdownButton *countdownButton;

@end

@implementation SecondViewController

#pragma mark - Life Cicle

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    self.title = @"第二页";
    
    self.countdownButton = [[CQCountdownButton alloc] initWithFrame:CGRectMake(90, 200, 200, 30)];
    [self.view addSubview:self.countdownButton];
    [self.countdownButton setTitle:@"点击获取验证码" forState:UIControlStateNormal];
    self.countdownButton.backgroundColor = [UIColor blueColor];
    self.countdownButton.dataSource = self;
    self.countdownButton.delegate = self;
}

- (void)dealloc {
    [self.countdownButton releaseTimer];
    NSLog(@"页面二已释放");
}

#pragma mark - CQCountdownButton DataSource

// 设置倒计时总秒数
- (NSInteger)startCountdownNumOfCountdownButton:(CQCountdownButton *)countdownButton {
    return 60;
}

#pragma mark - CQCountdownButton Delegate

// 倒计时按钮点击
- (void)countdownButtonDidClick:(CQCountdownButton *)countdownButton {
    // 按钮点击后将enabled设置为NO
    countdownButton.enabled = NO;
    countdownButton.backgroundColor = [UIColor grayColor];
    // 请求短信验证码
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [countdownButton startCountDown];
    });
}

// 倒计时进行中
- (void)countdownButtonDidCountdown:(CQCountdownButton *)countdownButton withRestCountdownNum:(NSInteger)restCountdownNum {
    NSString *title = [NSString stringWithFormat:@"%ld秒后重新获取", restCountdownNum];
    [countdownButton setTitle:title forState:UIControlStateNormal];
}

// 倒计时结束
- (void)countdownButtonDidEndCountdown:(CQCountdownButton *)countdownButton {
    [self.countdownButton setTitle:@"点击获取验证码" forState:UIControlStateNormal];
    countdownButton.backgroundColor = [UIColor blueColor];
    countdownButton.enabled = YES;
}

@end

这个倒计时button的具体实现如下：

#import "CQCountdownButton.h"

@interface CQCountdownButton ()

@property (nonatomic, strong) NSTimer *timer;

@end

@implementation CQCountdownButton {
    // 剩余倒计时
    NSInteger _restCountDownNum;
}

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        [self addTarget:self action:@selector(onClick) forControlEvents:UIControlEventTouchUpInside];
    }
    return self;
}

// 按钮点击
- (void)onClick {
    if ([self.dataSource respondsToSelector:@selector(startCountdownNumOfCountdownButton:)]) {
        _restCountDownNum = [self.dataSource startCountdownNumOfCountdownButton:self];
    }
    if ([self.delegate respondsToSelector:@selector(countdownButtonDidClick:)]) {
        [self.delegate countdownButtonDidClick:self];
    }
}

// 开始倒计时
- (void)startCountDown {
    if (self.timer) {
        [self releaseTimer];
    }
    
    self.timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(refreshButton) userInfo:nil repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
}

// 刷新按钮
- (void)refreshButton {
    _restCountDownNum --;
    
    if ([self.delegate respondsToSelector:@selector(countdownButtonDidCountdown:withRestCountdownNum:)]) {
        [self.delegate countdownButtonDidCountdown:self withRestCountdownNum:_restCountDownNum];
    }
    
    if (_restCountDownNum == 0) {
        [self releaseTimer];
        
        if ([self.delegate respondsToSelector:@selector(countdownButtonDidEndCountdown:)]) {
            [self.delegate countdownButtonDidEndCountdown:self];
        }
    }
}

- (void)releaseTimer {
    if (self.timer) {
        [self.timer invalidate];
        self.timer = nil;
    }
}

- (void)dealloc {
    NSLog(@"倒计时按钮已释放");
}

@end

demo：
https://github.com/CaiWanFeng/ClearCountdownButton