ios NSTimer定时器

做了一个非常简单的关于定时器的demo，效果如图，点击start timer，两个矩形开始移动，添加了一些碰撞检测，即两个矩形相碰或碰到边界会弹回，点击stop timer定时器停止。

效果图

在ViewController.h中，定义定时器变量

//ViewController.h
#import <UIKit/UIKit.h>
//所有的控制器都需要自定义来完成
//继承于官方的UIViewController
@interface ViewController : UIViewController{
    //定义一个定时器对象
    //可以在每隔固定的时间发送一个消息，通过此消息调用相应的函数
    NSTimer* _timerView;

    int direction1_x;  //标记view1 xy方向
    int direction1_y;
    int direction2_x;  //标记view2 xy方向
    int direction2_y;
    int speed_x;      //标记xy方向上的移动速度
    int speed_y;
}
@property (retain,nonatomic) NSTimer* timerView;
@end

在ViewController.m中实现

#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
//属性和成员函数的同步
@synthesize timerView = _timerView;

-(void) creatTimer{
   //创建startTimer按钮 ，并设置按下的触发事件，启动定时器
    UIButton* btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    btn.frame = CGRectMake(100, 100, 80, 40);
    [btn setTitle:@"start timer" forState:UIControlStateNormal];
    [btn addTarget:self action:@selector(pressStart) forControlEvents:UIControlEventTouchUpInside];
    //创建stopTimer按钮
    UIButton* btnStop = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    btnStop.frame = CGRectMake(100, 200, 80, 40);
    [btnStop setTitle:@"stop Timer" forState:UIControlStateNormal];
    [btnStop addTarget:self action:@selector(pressStop)  forControlEvents:UIControlEventTouchUpInside];
    
    [self.view addSubview:btn];
    [self.view addSubview:btnStop];
    
    //创建两个view，矩形
    UIView* view1 = [[UIView alloc] init];
    view1.frame = CGRectMake(30, 30, 80, 80);
    view1.backgroundColor = [UIColor orangeColor];
    [self.view addSubview:view1];
    
    UIView* view2 = [[UIView alloc] init];
    view2.frame = CGRectMake(80, 200, 40, 40);
    view2.backgroundColor = [UIColor blueColor];
    [self.view addSubview:view2];
    
    //设置view的标签值，通过父亲视图对象以及view的标签值可以获得相应的视图对象
    view1.tag=101;
    view2.tag=102;

    direction1_x=1;  //标记view1 xy方向
    direction1_y=1;
    direction2_x=1;  //标记view2 xy方向
    direction2_y=1;
    speed_x=5;      //标记xy方向上的移动速度
    speed_y=5;
}

-(void) pressStart{
    //nstimer的类方法创建一个定时器并且启动这个定时器
    //P1 每隔多长时间调用一次定时器函数，以秒为单位
    //P2 表示实现定时器函数的对象
    //P3 对象实现的函数
    //P4 传参
    //P5 定时器是否重复操作
    //返回值为一个新创建好的定时器
    _timerView = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(updateTimer:) userInfo:@"Johnny" repeats:YES];
}

-(void) pressStop{
    //停止定时器
    if (_timerView != nil){
        [_timerView invalidate];
    }
}

//定时器的触发函数，定时器本身作为参数传递过来
-(void) updateTimer:(NSTimer*) timer{
    //NSLog(@"timerStart test name = %@",timer.userInfo);
    UIView* view1 = [self.view viewWithTag:101];
    UIView* view2 = [self.view viewWithTag:102];
   //检测两个矩形是否相交，若相交则方向取反
    [self checkCollopse:view1 view2:view2];
   //移动两个矩形，并判断是否与边界相交，若相交方向取反
   //两个矩形调用同一个方法，两个矩形使用不同的direction值，将各自的direction以指针传递过去
    [self checkBorder:view1 direction_x:&direction1_x direction_y:&direction1_y];
    [self checkBorder:view2 direction_x:&direction2_x direction_y:&direction2_y];
}

//检测两个矩形view是否相交，若不相交返回false，相交则将direction取反，返回true
-(bool) checkCollopse:(UIView*) view1 view2:(UIView*) view2{
    int x1 = view1.frame.origin.x;
    int y1 = view1.frame.origin.y;
    int x2 = view2.frame.origin.x;
    int y2 = view2.frame.origin.y;
    int w1 = view1.frame.size.width;
    int h1 = view1.frame.size.height;
    int w2 = view2.frame.size.width;
    int h2 = view2.frame.size.height;
    //检测一定不相交的情况
    if ((x1 + w1) < x2 || (x2 + w2) < x1 || (y1 + h1) < y2 || (y2 + h2) < y1){
        //不相交
        return false;
    }else{
        if ((x1 + w1) <= x2 || (x2 + w2) <= x1){
            //x相交
            direction1_x = -direction1_x;
            direction2_x = -direction2_x;
        }else{
            //y相交
            direction1_y = -direction1_y;
            direction2_y = -direction2_y;
        }
        return true;
    }
}

//检测view的范围，碰到边界返回
-(void) checkBorder:(UIView*) view direction_x:(int *)direction_x  direction_y:(int *)direction_y{
    if (view.frame.origin.x+view.frame.size.width >= self.view.frame.size.width || view.frame.origin.x <= 0){
        *direction_x = -*direction_x;
    }
    if (view.frame.origin.y+view.frame.size.height >= self.view.frame.size.height || view.frame.origin.y <= 0){
        *direction_y = -*direction_y;
    }
    int x_move = *direction_x*speed_x, y_move = *direction_y*speed_y;
    view.frame = CGRectMake(view.frame.origin.x+x_move, view.frame.origin.y+y_move, view.frame.size.width, view.frame.size.height);    
}

//当视图控制器第一次被加载显示视图时，调用此函数
//布局初始化视图来使用，初始化资源使用
- (void)viewDidLoad {
    //定时器函数
    [self creatTimer];
}