线程之间的通信

<p>线程间通信：在1个进程中，线程往往不是孤立存在的，多个线程之间需要经常进行通信</p><p> </p><p>线程间通信的体现</p><p>1个线程传递数据给另1个线程</p><p>在1个线程中执行完特定任务后，转到另1个线程继续执行任务</p>#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.        SEL sel[3] = {      @selector(nsthread),        @selector(gcd),        @selector(operationQueue)    };        for (NSInteger i = 0; i < 3; i++) {        NSThread *th = [[NSThread alloc]initWithTarget:self selector:sel[i] object:nil];        [th start];    }}#pragma mark -线程通信（主线程）--(void)nsthread{    //NSThread 获取主线程的方法    [self performSelectorOnMainThread:@selector(finish) withObject:self waitUntilDone:NO];        //下面这条语句还是子线程 ！！！！     NSLog(@"nsthread%@",[NSThread currentThread]);}-(void)gcd{    //GCD获取主线程的方法    dispatch_async(dispatch_get_main_queue(), ^{        NSLog(@"gcd%@",[NSThread currentThread]);        [self finish];    });}-(void)operationQueue{    //NSOperationQueue 获取主队列    NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];    [mainQueue addOperationWithBlock:^{        NSLog(@"mainQueue%@",[NSThread currentThread]);        [self finish];    }];}-(void)finish{    NSLog(@"完成!!!!!!");}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end