ios中多線程的摘錄

簡書中比較全的多線程執行，在這裏保存下鏈接傳送門

//
//  ViewController.m
//  syn_asyn
//
//  Created by mac on 2018/6/20.
//  Copyright © 2018年 Gooou. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // 使用 NSThread 的 detachNewThreadSelector 方法會創建線程，並自動啓動線程執行 selector 任務,不會造成卡頓，任務三個都加在主線程中執行，而主線程沒有任務執行，所以不會造成崩潰。
//    [NSThread detachNewThreadSelector:@selector(sync_mainQueue) toTarget:self withObject:nil];
    [self groupEnterAndLeave];
}
/*同步執行，併發隊列*/
-(void)sync_ConcurrentQueue{
    NSLog(@"currentThread--%@",[NSThread currentThread]);//打印當前線程
    NSLog(@"syncConcurrent--begin");
    //串行隊列
    dispatch_queue_t queue=dispatch_queue_create("net.bujige.testQueue", DISPATCH_QUEUE_CONCURRENT);
    //同步執行
    dispatch_sync(queue, ^{
        //追加任務
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];//模擬操作耗時
            NSLog(@"1--%@",[NSThread currentThread]);//打印當前線程
        }
    });

    dispatch_sync(queue, ^{
        //追加任務2
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"2--%@",[NSThread currentThread]);
        }
    });

    dispatch_sync(queue, ^{
        //追加任務3
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"3--%@",[NSThread currentThread]);
        }
    });
    NSLog(@"syncConcurrent--end");
}
/*異步執行併發隊列:可開啓多個線程，任務交替執行*/
-(void)async_ConcurrentQueue{
    /*異步執行+併發隊列
     特點：可以開啓多個線程，任務交替執行
     */
    NSLog(@"currentThread--%@",[NSThread currentThread]);
    NSLog(@"asyncConcurrent--begin");

    dispatch_queue_t queue=dispatch_queue_create("net.bujige.testQueue",DISPATCH_QUEUE_CONCURRENT);
    dispatch_async(queue, ^{
        //追加任務
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];//模擬操作耗時
            NSLog(@"1--%@",[NSThread currentThread]);//打印當前線程
        }
    });

    dispatch_async(queue, ^{
        //追加任務2
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"2--%@",[NSThread currentThread]);
        }
    });

    dispatch_async(queue, ^{
        //追加任務3
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"3--%@",[NSThread currentThread]);
        }
    });
    NSLog(@"asyncConcurrent--end");
}
/*同步執行+串行隊列*/
-(void)sync_serialQueue{
    NSLog(@"currentThread--%@",[NSThread currentThread]);
    NSLog(@"syncConcurrent--begin");

    dispatch_queue_t queue=dispatch_queue_create("net.bujige.testQueue",DISPATCH_QUEUE_SERIAL);
    dispatch_sync(queue, ^{
        //追加任務
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];//模擬操作耗時
            NSLog(@"1--%@",[NSThread currentThread]);//打印當前線程
        }
    });

    dispatch_sync(queue, ^{
        //追加任務2
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"2--%@",[NSThread currentThread]);
        }
    });

    dispatch_sync(queue, ^{
        //追加任務3
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"3--%@",[NSThread currentThread]);
        }
    });
    NSLog(@"syncConcurrent--end");
}
/*異步執行+串行隊列*/
-(void)async_serialQueue{
    NSLog(@"currentThread--%@",[NSThread currentThread]);
    NSLog(@"asyncConcurrent--begin");

    dispatch_queue_t queue=dispatch_queue_create("net.bujige.testQueue",DISPATCH_QUEUE_SERIAL);
    dispatch_async(queue, ^{
        //追加任務
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];//模擬操作耗時
            NSLog(@"1--%@",[NSThread currentThread]);//打印當前線程
        }
    });

    dispatch_async(queue, ^{
        //追加任務2
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"2--%@",[NSThread currentThread]);
        }
    });

    dispatch_async(queue, ^{
        //追加任務3
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"3--%@",[NSThread currentThread]);
        }
    });
    NSLog(@"asyncConcurrent--end");
}
/*同步執行+主隊列
 特點:互相等待卡主不執行
      不會開啓新線程，執行完一個任務，執行下一個任務
      會產生崩潰
 */
-(void)sync_mainQueue{
    NSLog(@"currentThread--%@",[NSThread currentThread]);
    NSLog(@"syncMain--begin");

    dispatch_queue_t queue=dispatch_get_main_queue();

    dispatch_async(queue, ^{
        //追加任務
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];//模擬操作耗時
            NSLog(@"1--%@",[NSThread currentThread]);//打印當前線程
        }
    });

    dispatch_sync(queue, ^{
        //追加任務2
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"2--%@",[NSThread currentThread]);
        }
    });

    dispatch_sync(queue, ^{
        //追加任務3
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"3--%@",[NSThread currentThread]);
        }
    });
    NSLog(@"syncMain--end");
}
/*異步執行+主隊列
 只在主線程執行任務，執行完一個任務，再執行下一個任務
 所有任務都是在當前線程（主線程）中執行的，並沒有開啓新的線程（雖然異步執行具備開啓線程的能力，但因爲是主隊列，所以所有任務都在主線程中）
 */
-(void)async_mainQueue{
    NSLog(@"currentThread--%@",[NSThread currentThread]);
    NSLog(@"asyncMain--begin");

    dispatch_queue_t queue=dispatch_get_main_queue();

    dispatch_async(queue, ^{
        //追加任務
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];//模擬操作耗時
            NSLog(@"1--%@",[NSThread currentThread]);//打印當前線程
        }
    });

    dispatch_async(queue, ^{
        //追加任務2
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"2--%@",[NSThread currentThread]);
        }
    });

    dispatch_async(queue, ^{
        //追加任務3
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"3--%@",[NSThread currentThread]);
        }
    });
    NSLog(@"asyncMain--end");
}
/*
 線程間的通訊
 */
-(void)communication{
   //獲取全局併發隊列
    dispatch_queue_t queue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //獲取主隊列
    dispatch_queue_t mainQueue=dispatch_get_main_queue();

    dispatch_async(queue, ^{
       //異步追加任務
        for (int i=0; i<2; ++i) {
            [NSThread sleepForTimeInterval:2];
            NSLog(@"1--%@",[NSThread currentThread]);
        }
        //回到主線程
        dispatch_async(mainQueue, ^{
           //追加在主線程中執行的任務
            [NSThread sleepForTimeInterval:2];
            NSLog(@"2--%@",[NSThread currentThread]);
        });
    });
}
/*
 柵欄方法：需要異步執行兩組操作，而且第一組操作完成之後，才能開始執行第二組操作，
 */
-(void)barrier{
    dispatch_queue_t queue = dispatch_queue_create("net.bujige.testQueue", DISPATCH_QUEUE_CONCURRENT);
    dispatch_async(queue, ^{
        // 追加任務1
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2]; // 模擬耗時操作
            NSLog(@"1---%@",[NSThread currentThread]);// 打印當前線程
        }
    });
    dispatch_async(queue, ^{
        // 追加任務2
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2]; // 模擬耗時操作
            NSLog(@"2---%@",[NSThread currentThread]);// 打印當前線程
        }
    });
    dispatch_barrier_sync(queue, ^{
        // 追加任務 barrier
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2]; // 模擬耗時操作
            NSLog(@"barrier---%@",[NSThread currentThread]);// 打印當前線程
        }
    });
    dispatch_async(queue, ^{
        // 追加任務3
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2]; // 模擬耗時操作
            NSLog(@"3---%@",[NSThread currentThread]);// 打印當前線程
        }
    });
    dispatch_async(queue, ^{
        // 追加任務4
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2]; // 模擬耗時操作
            NSLog(@"4---%@",[NSThread currentThread]);// 打印當前線程
        }
    });
}
/*
 延時執行方法
 */
-(void)after{
    NSLog(@"currentThread--%@",[NSThread currentThread]);
    NSLog(@"asyncMain--begin");

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0*NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        //2.0秒之後異步追加任務到主隊列中，並開始執行
        NSLog(@"after--%@",[NSThread currentThread]);
    });
}
/*只執行一次
 多線程環境下，保證線程安全
 */
-(void)once{
    static dispatch_queue_t onceToken;
//    dispatch_once(&onceToken, ^{
//       //執行代碼
//    });
}
/*
 dispatch_apply按照指定的次數將指定的任務添加到指定的隊列中取，並等待全部隊列執行結束
 */
-(void)apply{
    dispatch_queue_t queue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    NSLog(@"apply--begin");

    dispatch_apply(6, queue, ^(size_t index) {
        NSLog(@"%zd--%@",index,[NSThread currentThread]);
    });
    NSLog(@"apply--end");
}
/*
 分別異步執行2個耗時任務，然後當2個耗時任務執行完成之後回到主線程執行任務。
 */
-(void)groupNofity{
    NSLog(@"currentThread---%@",[NSThread currentThread]);  // 打印當前線程
    NSLog(@"group---begin");

    dispatch_group_t group=dispatch_group_create();

    dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // 追加任務1
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"1---%@",[NSThread currentThread]);      // 打印當前線程
        }
    });
    dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // 追加任務2
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"2---%@",[NSThread currentThread]);      // 打印當前線程
        }
    });
    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        // 等前面的異步任務1、任務2都執行完畢後，回到主線程執行下邊任務
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"3---%@",[NSThread currentThread]);      // 打印當前線程
        }
        NSLog(@"group---end");
    });
}
/*暫停當前線程，等待指定的group中的任務執行完成後，纔會往下執行
 */
-(void)groupWait{
    NSLog(@"currentThread---%@",[NSThread currentThread]);  // 打印當前線程
    NSLog(@"group---begin");

    dispatch_group_t group=dispatch_group_create();

    dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // 追加任務1
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"1---%@",[NSThread currentThread]);      // 打印當前線程
        }
    });

    dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // 追加任務1
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"2---%@",[NSThread currentThread]);      // 打印當前線程
        }
    });

    //等待上面的任務全部完成後，會往下繼續執行(會阻塞當前線程)
    dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
     NSLog(@"group---end");
}
- (void)groupEnterAndLeave
{
    NSLog(@"currentThread---%@",[NSThread currentThread]);  // 打印當前線程
    NSLog(@"group---begin");

    dispatch_group_t group = dispatch_group_create();
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_group_enter(group);
    dispatch_async(queue, ^{
        // 追加任務1
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"1---%@",[NSThread currentThread]);      // 打印當前線程
        }
        dispatch_group_leave(group);
    });

    dispatch_group_enter(group);
    dispatch_async(queue, ^{
        // 追加任務2
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"2---%@",[NSThread currentThread]);      // 打印當前線程
        }
        dispatch_group_leave(group);
    });

    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        // 等前面的異步操作都執行完畢後，回到主線程.
        for (int i = 0; i < 2; ++i) {
            [NSThread sleepForTimeInterval:2];              // 模擬耗時操作
            NSLog(@"3---%@",[NSThread currentThread]);      // 打印當前線程
        }
        NSLog(@"group---end");
    });

}
@end