iOS實(shí)現(xiàn)倒計(jì)時(shí)的三種方式

做iOS app開(kāi)發(fā)的過(guò)程當(dāng)中，經(jīng)常會(huì)出現(xiàn)獲取驗(yàn)證碼等需求，這個(gè)時(shí)候一般會(huì)使用倒計(jì)時(shí)來(lái)提示用戶，本文主要總結(jié)iOS開(kāi)發(fā)中常用的三種倒計(jì)時(shí)的實(shí)現(xiàn)方式。

Thread方式實(shí)現(xiàn)

NSTimer方式實(shí)現(xiàn) (此種方式實(shí)現(xiàn)的時(shí)候，要注意Timer invalidate的時(shí)機(jī)，防止循環(huán)引用)

GCD方式實(shí)現(xiàn)

直接上代碼吧

#define TIMECOUNT 60

@interface ViewController ()
@property (strong, nonatomic) IBOutlet UIButton *firstBtn;
@property (strong, nonatomic) IBOutlet UIButton *secondBtn;
@property (strong, nonatomic) IBOutlet UIButton *thirdBtn;

@property (assign, nonatomic) int count;
@property (nonatomic, strong) NSTimer *timer;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.count = TIMECOUNT;
}

- (void)viewDidDisappear:(BOOL)animated {
    //頁(yè)面消失的時(shí)候暫停定時(shí)器，防止出現(xiàn)循環(huán)引用，導(dǎo)致內(nèi)存泄漏
    [self.timer invalidate];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

//------------***第一種方法***------------
#pragma mark 線程Thread方式實(shí)現(xiàn)
- (IBAction)firstBtnAction:(id)sender {
    //創(chuàng)建一個(gè)后臺(tái)線程執(zhí)行計(jì)時(shí)操作
    [self performSelectorInBackground:@selector(timerThread) withObject:nil];
}

- (void)timerThread {
    for (int i = TIMECOUNT; i >= 0 ; i--) {
        self.count--;
        //切換到主線程中更新UI
        [self performSelectorOnMainThread:@selector(updateFirstBtn) withObject:nil waitUntilDone:YES];
        sleep(1);
    }
}

//更新UI
- (void)updateFirstBtn {
    NSString *str = nil;
    if (self.count == 0) {
        str = [NSString stringWithFormat:@"點(diǎn)擊獲取驗(yàn)證碼"];
        self.firstBtn.userInteractionEnabled = YES;
    } else {
        str = [NSString stringWithFormat:@"%d秒后重新獲取",self.count];
        self.firstBtn.userInteractionEnabled = NO;
    }
    [self.firstBtn setTitle:str forState:UIControlStateNormal];
}

//------------***第二種方法***------------
#pragma mark NSTimer實(shí)現(xiàn)
- (IBAction)secondBtnAction:(id)sender {
    self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(handleTimer) userInfo:nil repeats:YES];
}
//定時(shí)操作，更新UI
- (void)handleTimer {
    if (self.count == 0) {
        self.secondBtn.userInteractionEnabled = YES;
        [self.secondBtn setTitle:[NSString stringWithFormat:@"點(diǎn)擊獲取驗(yàn)證碼"] forState:UIControlStateNormal];
        self.count = TIMECOUNT;
        [self.timer invalidate];
    } else {
        self.secondBtn.userInteractionEnabled = NO;
        [self.secondBtn setTitle:[NSString stringWithFormat:@"%d秒后重新獲取",self.count] forState:UIControlStateNormal];
    }
    self.count--;
}

//------------***第三種方法***------------
/**
 *  1、獲取或者創(chuàng)建一個(gè)隊(duì)列，一般情況下獲取一個(gè)全局的隊(duì)列
 *  2、創(chuàng)建一個(gè)定時(shí)器模式的事件源
 *  3、設(shè)置定時(shí)器的響應(yīng)間隔
 *  4、設(shè)置定時(shí)器事件源的響應(yīng)回調(diào)，當(dāng)定時(shí)事件發(fā)生時(shí)，執(zhí)行此回調(diào)
 *  5、啟動(dòng)定時(shí)器事件
 *  6、取消定時(shí)器dispatch源，【必須】
 *
 */
#pragma mark GCD實(shí)現(xiàn)
- (IBAction)thirdBtnAction:(id)sender {
    __block NSInteger second = TIMECOUNT;
    //(1)
    dispatch_queue_t quene = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //(2)
    dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, quene);
    //(3)
    dispatch_source_set_timer(timer, DISPATCH_TIME_NOW, 1 * NSEC_PER_SEC, 0 * NSEC_PER_SEC);
    //(4)
    dispatch_source_set_event_handler(timer, ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (second == 0) {
                self.thirdBtn.userInteractionEnabled = YES;
                [self.thirdBtn setTitle:[NSString stringWithFormat:@"點(diǎn)擊獲取驗(yàn)證碼"] forState:UIControlStateNormal];
                second = TIMECOUNT;
                //(6)
                dispatch_cancel(timer);
            } else {
                self.thirdBtn.userInteractionEnabled = NO;
                [self.thirdBtn setTitle:[NSString stringWithFormat:@"%ld秒后重新獲取",second] forState:UIControlStateNormal];
                second--;
            }
        });
    });
    //(5)
    dispatch_resume(timer);
}

@end