本文介绍多种多线程方法：xoxo_x总结
本文总结的几种多线程创建方法均为异步线程，除了最后GCD的同步线程外。

第一种：

NSThread *thread = [[NSThread alloc]initWithBlock:^{

        NSLog(@"线程1");
    }];
    [thread start];
    NSLog(@"主线程");

第二种：

[NSThread detachNewThreadWithBlock:^{
         NSLog(@"线程2");
    }];
    NSLog(@"主线程");

第三种：

 [self performSelector:@selector(doLog) withObject:self afterDelay:2];
    NSLog(@"主线程");

- (void)doLog{
    NSLog(@"线程3");
}

第四种：

NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [queue addOperationWithBlock:^{
        NSLog(@"线程4");
    }];
    NSLog(@"主线程");

第五种：

NSOperationQueue *operaQueue = [[NSOperationQueue alloc]init];
    NSInvocationOperation *op = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(doLog1) object:nil];
    [operaQueue addOperation:op];
    NSLog(@"主线程");
//maxConcurrentOperationCount 并发数量
//qualityOfService 优先级

- (void)doLog1{
    NSLog(@"线程5");
}

第六种：

//  ---------------GCD-----------------------
    //第六种
    dispatch_queue_t queue2 = dispatch_queue_create("queue", NULL);
    dispatch_async(queue2, ^{
        NSLog(@"线程6");
    });
    NSLog(@"主线程");

    //同步线程
    dispatch_sync(queue2, ^{
        NSLog(@"线程7");
    });
    NSLog(@"主线程");

关于NSThread：

//获取当前线程
@property (class, readonly, strong) NSThread *currentThread;
//是否多线程
+ (BOOL)isMultiThreaded;
//创建方法 静态和动态创建
+ (void)detachNewThreadWithBlock:(void (^)(void))block API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0));
+ (void)detachNewThreadSelector:(SEL)selector toTarget:(id)target withObject:(nullable id)argument;

- (instancetype)initWithTarget:(id)target selector:(SEL)selector object:(nullable id)argument NS_AVAILABLE(10_5, 2_0);
- (instancetype)initWithBlock:(void (^)(void))block API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0));

//取消、开始
- (void)cancel NS_AVAILABLE(10_5, 2_0);

- (void)start NS_AVAILABLE(10_5, 2_0);



//获取主线程
- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullable id)arg waitUntilDone:(BOOL)wait modes:(nullable NSArray<NSString *> *)array;

- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullable id)arg waitUntilDone:(BOOL)wait;

关于NSOperationQueue：

//设置最大并发数量
@property NSInteger maxConcurrentOperationCount;
//设置优先级
@property NSQualityOfService qualityOfService NS_AVAILABLE(10_10, 8_0);
//创建
- (void)addOperation:(NSOperation *)op;
- (void)addOperations:(NSArray<NSOperation *> *)ops waitUntilFinished:(BOOL)wait NS_AVAILABLE(10_6, 4_0);

- (void)addOperationWithBlock:(void (^)(void))block NS_AVAILABLE(10_6, 4_0);

关于 NSInvocationOperation：
如果说NSOperationQueue是线程队列，那么NSInvocationOperation就是一个个的队员。

//继承 ： NSOperation
@interface NSInvocationOperation : NSOperation 
//创建方法
- (nullable instancetype)initWithTarget:(id)target selector:(SEL)sel object:(nullable id)arg;
- (instancetype)initWithInvocation:(NSInvocation *)inv NS_DESIGNATED_INITIALIZER;

关于GCD:

//创建线程
dispatch_queue_create(const char *_Nullable label,dispatch_queue_attr_t _Nullable attr);
//创建异步线程方法
void
dispatch_async(dispatch_queue_t queue, dispatch_block_t block);
//创建同步线程
dispatch_sync(dispatch_queue_t queue, DISPATCH_NOESCAPE dispatch_block_t block);
//回到主线程
dispatch_get_main_queue()

log信息：

2017-02-27 01:47:36.245 Queue[13909:903388] 主线程
2017-02-27 01:47:36.245 Queue[13909:903494] 线程1
2017-02-27 01:47:36.245 Queue[13909:903388] 主线程
2017-02-27 01:47:36.245 Queue[13909:903495] 线程2
2017-02-27 01:47:36.245 Queue[13909:903388] 主线程
2017-02-27 01:47:36.246 Queue[13909:903388] 主线程
2017-02-27 01:47:36.246 Queue[13909:903428] 线程4
2017-02-27 01:47:36.246 Queue[13909:903388] 主线程
2017-02-27 01:47:36.246 Queue[13909:903428] 线程5
2017-02-27 01:47:36.246 Queue[13909:903388] 主线程
2017-02-27 01:47:36.246 Queue[13909:903442] 线程6
2017-02-27 01:47:36.246 Queue[13909:903388] 线程7
2017-02-27 01:47:36.246 Queue[13909:903388] 主线程
2017-02-27 01:47:38.245 Queue[13909:903388] 线程3

本文涉及的全部代码：

//
//  ViewController.m
//  Queue
//
//  Created by 冯士魁 on 2017/2/27.
//  Copyright © 2017年 xoxo_x. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //第一种
    NSThread *thread = [[NSThread alloc]initWithBlock:^{

        NSLog(@"线程1");
    }];
    [thread start];
    NSLog(@"主线程");


    [thread isMainThread];//判断是否为主线程


    //第二种
    [NSThread detachNewThreadWithBlock:^{
         NSLog(@"线程2");
    }];
    NSLog(@"主线程");

    //第三种
    [self performSelector:@selector(doLog) withObject:self afterDelay:2];
    NSLog(@"主线程");


    //第四种
    NSOperationQueue *queue = [[NSOperationQueue alloc]init];
    [queue addOperationWithBlock:^{
        NSLog(@"线程4");
    }];
    NSLog(@"主线程");

    //第五种
    NSOperationQueue *operaQueue = [[NSOperationQueue alloc]init];
    NSInvocationOperation *op = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(doLog1) object:nil];
    [operaQueue addOperation:op];
    NSLog(@"主线程");
    //maxConcurrentOperationCount 并发数量
    //qualityOfService 优先级

    //  ---------------GCD-----------------------
    //第六种
    dispatch_queue_t queue2 = dispatch_queue_create("queue", NULL);
    dispatch_async(queue2, ^{
        NSLog(@"线程6");
    });
    NSLog(@"主线程");
    //同步线程
    dispatch_sync(queue2, ^{
        NSLog(@"线程7");
    });
    NSLog(@"主线程");

}

- (void)doLog{
    NSLog(@"线程3");
}
- (void)doLog1{
    NSLog(@"线程5");
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end