NSThread中cancle与exit的使用

    @interface ViewController ()      /** 图片视图*/    @property(nonatomic,weak) UIImageView * imageView;      /** 图片数组*/    @property(nonatomic,strong) NSMutableArray * imageArray;      /** 存储线程*/    @property(nonatomic,strong) NSMutableArray * threadArray;      @end      //对象方法cancle，可以在外部使用。    //类方法exit，写在线程内部，结束当前现线程。    //两者结合使用，使用cancle进行标记，使用exit退出      @implementation ViewController    - (NSMutableArray *)imageArray    {        if (_imageArray==nil) {            _imageArray =[NSMutableArray array];        }        return _imageArray;    }      - (NSMutableArray *)threadArray    {        if (_threadArray==nil) {            _threadArray =[NSMutableArray array];        }        return _threadArray;    }      - (void)viewDidLoad    {        [super viewDidLoad];                //加载视图        [self _loadViews];                //开启多线程加载图片        [self _openMultiThread];        }      //======加载这个，可以在主线程中加载    - (void) _loadViews    {        for (int i=0;i<15; i++)        {            int col=i%3;            int row=i/3;                        UIImageView *imageView=[[UIImageView alloc] initWithFrame:CGRectMake(22+col*(80+45), 40+row*(100+20), 90, 90)];            imageView.backgroundColor=[UIColor redColor];            [self.imageArray addObject:imageView];                        [self.view addSubview:imageView];        }    //    添加按钮         UIButton * button=[UIButton buttonWithType:UIButtonTypeContactAdd];         button.frame=CGRectMake(0, 20, 20, 20);         [button addTarget:self action:@selector(btClick) forControlEvents:UIControlEventTouchUpInside];         [self.view addSubview:button];        }      //开启多线程加载图片    - (void) _openMultiThread    {        for (int i=0; i<self.imageArray.count; i++)        {    //        [NSThread detachNewThreadSelector:@selector(loadImage:) toTarget:self withObject:@(i)];                //        要存数组就不能使用类方法创建线程            NSThread * thread = [[NSThread alloc] initWithTarget:self selector:@selector(loadImage:) object:@(i)];            [thread start];            [self.threadArray addObject:thread];        }    }          - (void)loadImage:(NSNumber *) number    {        //取到索引        NSInteger index=[number integerValue];               NSString * imageSrc=@"http://images.cnblogs.com/cnblogs_com/kenshincui/613474/o_%d.jpg";                imageSrc=[NSString stringWithFormat:imageSrc,index];                        NSURL * URL=[NSURL URLWithString:imageSrc];        NSData * data=[NSData dataWithContentsOfURL:URL];        UIImage *image=[UIImage imageWithData:data];                //封装model        ImageModel * model=[[ImageModel alloc] init];        model.image=image;        model.index=index;               //如果状态为删除，则退出线程        NSThread * thread = [NSThread currentThread];        if ([thread isCancelled])        {            [NSThread exit];//执行exit，后边的语句不再执行。所以不用写return        //return也可以退出进程，一旦退出就不能再使用start开启        }        NSLog(@"%@", thread);        [self performSelectorOnMainThread:@selector(showImage:) withObject:model waitUntilDone:NO];    }      //回到主线程更新图片    - (void) showImage:(ImageModel *) model    {        UIImageView * imageView=self.imageArray[model.index];        imageView.image=model.image;    }        #pragma mark - 点击事件    - (void)btClick    {    //    当点击按钮时，对所有线程进行标记        for (NSThread * t in self.threadArray)        {            [t cancel];        }    }
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NSThread中cancle与exit的使用
