iOS 倒计时 三种方式
#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 {
//页面消失的时候暂停定时器，防止出现循环引用，导致内存泄漏
[self.timer invalidate];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
//------------***第一种方法***------------
#pragma mark 线程Thread方式实现
- (IBAction)firstBtnAction:(id)sender {
//创建一个后台线程执行计时操作
[self performSelectorInBackground:@selector(timerThread) withObject:nil];
}
- (void)timerThread {
for (int i = TIMECOUNT; i >= 0 ; i--) {
self.count--;
//切换到主线程中更新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:@"点击获取验证码"];
self.firstBtn.userInteractionEnabled = YES;
} else {
str = [NSString stringWithFormat:@"%d秒后重新获取",self.count];
self.firstBtn.userInteractionEnabled = NO;
}
[self.firstBtn setTitle:str forState:UIControlStateNormal];
}
//------------***第二种方法***------------
//NSTimer方式实现 (此种方式实现的时候，要注意Timer invalidate的时机，防止循环引用)
#pragma mark NSTimer实现
- (IBAction)secondBtnAction:(id)sender {
self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(handleTimer) userInfo:nil repeats:YES];
}
//定时操作，更新UI
- (void)handleTimer {
if (self.count == 0) {
self.secondBtn.userInteractionEnabled = YES;
[self.secondBtn setTitle:[NSString stringWithFormat:@"点击获取验证码"] forState:UIControlStateNormal];
self.count = TIMECOUNT;
[self.timer invalidate];
} else {
self.secondBtn.userInteractionEnabled = NO;
[self.secondBtn setTitle:[NSString stringWithFormat:@"%d秒后重新获取",self.count] forState:UIControlStateNormal];
}
self.count--;
}
//------------***第三种方法***------------
/**
* 1、获取或者创建一个队列，一般情况下获取一个全局的队列
* 2、创建一个定时器模式的事件源
* 3、设置定时器的响应间隔
* 4、设置定时器事件源的响应回调，当定时事件发生时，执行此回调
* 5、启动定时器事件
* 6、取消定时器dispatch源，【必须】
*
*/
#pragma mark GCD实现
- (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:@"点击获取验证码"] forState:UIControlStateNormal];
second = TIMECOUNT;
//(6)
dispatch_cancel(timer);
} else {
self.thirdBtn.userInteractionEnabled = NO;
[self.thirdBtn setTitle:[NSString stringWithFormat:@"%ld秒后重新获取",second] forState:UIControlStateNormal];
second--;
}
});
});
//(5)
dispatch_resume(timer);
}
@end
转载链接：https://www.jianshu.com/p/4ec7faeb0cd9