iOS - 定时器

头文件

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController{
    //头文件里定义计时器
    NSTimer* _timer;
}

//定义定时器属性
//retain 对NSObject对象复制
//nonatomic 单线程
@property(retain, nonatomic)NSTimer* timer;
@end

源文件

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

//属性与成员变量的映射/综合/同步
@synthesize timer = _timer;

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIButton* btn1 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    btn1.frame = CGRectMake(100, 100, 100, 100);
    [btn1 setTitle:@"start timer" forState:UIControlStateNormal];
    [btn1 addTarget:self action:@selector(btn1Click) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn1];
    
    UIButton* btn2 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    btn2.frame = CGRectMake(100, 220, 100, 100);
    [btn2 setTitle:@"end timer" forState:UIControlStateNormal];
    [btn2 addTarget:self action:@selector(btn2Click) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn2];
    
    [self initView];
}

-(void) initView{
    UIView* view = [[UIView alloc]init];
    view.frame = CGRectMake(0, 0, 50, 50);
    view.tag = 111;
    [view setBackgroundColor:[UIColor orangeColor]];
    [self.view addSubview:view];
    
}

-(void) btn1Click{
    NSLog(@"btn1Click");
    
    //通过NSTimer的类方法创建一个定时器
    _timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(onTimer:) userInfo:@"计时" repeats:YES];
}

int i = 0;
-(void) onTimer:(NSTimer*)timer{
    NSLog(@"onTimer %@ %d", timer.userInfo, i);
    i+=1;
    
    //UIView* view = [self.view viewWithTag:111];
    //view.frame = CGRectMake(view.frame.origin.x + 10, view.frame.origin.y +0.1f, 50, 50);
}

-(void) btn2Click{
    NSLog(@"btn2Click");
    if(_timer!=NULL){
        [_timer invalidate];
    }
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end