iOS开发多线程篇—创建线程

创建和启动线程简单说明

(1)线程的执行顺序由CPU负责，程序员不能保证线程的执行顺序，不能相信一次执行的结果

 NSThread *threadA = [[NSThread alloc] initWithTarget:self selector:@selector(longOperation:) object:@"hello I am threadA"];

(2)创建线程后自动启动线程   [NSThread detachNewThreadSelector:@selector(run) toTarget:self withObject:nil];

(3)隐式创建并启动线程  [self performSelectorInBackground:@selector(run) withObject:nil];

上述(2)(3)创建线程方式的优缺点

优点：简单快捷

缺点：无法对线程进行更详细的设置

 代码演示

//
//  ViewController.m
//  02NSThread
//
//  Created by mac on 15/10/9.
//  Copyright © 2015年 mac. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

//移除通知
- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:NSWillBecomeMultiThreadedNotification object:nil];
}
- (void)viewDidLoad {
    [super viewDidLoad];
    
    
//    FOUNDATION_EXPORT NSString * const NSWillBecomeMultiThreadedNotification;
//    FOUNDATION_EXPORT NSString * const NSDidBecomeSingleThreadedNotification;
//    FOUNDATION_EXPORT NSString * const NSThreadWillExitNotification;
    //注册通知(NSWillBecomeMultiThreadedNotification,是通知的名字，又系统发送，在程序开启子线程的时候发送该通知)
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(becomeMutipleThread) name:NSWillBecomeMultiThreadedNotification object:nil];
}

- (void)becomeMutipleThread
{
    NSLog(@"开启多线程");
}
//触摸屏幕执行此方法
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    /*
//    [self testOne];
    if ([NSThread isMultiThreaded]) {
        NSLog(@"是多线程");
    }else{
        NSLog(@"单线程");
    }//单线程

//    [self testTwo];
    [self threadProperty];
    
    if ([NSThread isMultiThreaded]) {
        NSLog(@"是多线程");
    }else{
        NSLog(@"单线程");
    }//多线程
*/
    
    [self nsobjectThread];
    
//    [self test];//在主线程中调用test方法
    
}

//线程的优先级
- (void)threadProperty
{
    
    //线程的执行顺序由CPU负责，程序员不能保证线程的执行顺序，不能相信一次执行的结果
      
    NSThread *threadA = [[NSThread alloc] initWithTarget:self selector:@selector(longOperation:) object:@"hello I am threadA"];
    
    
    threadA.name = @"ThreadA";
    //优先级：0.0~1.0，1.0是最高优先级
    [threadA setThreadPriority:1.0];
    
    [threadA start];
    
    NSThread *threadB = [[NSThread alloc] initWithTarget:self selector:@selector(longOperation:) object:@"hello I am threadB"];
    
    
    threadB.name = @"ThreadB";
    
    [threadB start];


}
- (void)nsobjectThread{

    //开启一个子线程调用longOperation:方法
    [self performSelectorInBackground:@selector(longOperation:) withObject:@"NSObject method"];
    //在主线程中调用
//    [self longOperation:@"main thread"];
    
}

//开启子线程2
- (void)testTwo {
    //开启一个子线程，并且执行
    [NSThread detachNewThreadSelector:@selector(longOperation:) toTarget:self withObject:@"hello"];
}

//开启子线程1
- (void)testOne {
    
//    NSThread
    //产生线程对象threadA----[target selector:argument]
    //- (instancetype)initWithTarget:(id)target selector:(SEL)selector object:(nullable id)argument;

 
    
    NSThread *threadA = [[NSThread alloc] initWithTarget:self selector:@selector(longOperation:) object:@"hello I am threadA"];
    
    
    threadA.name = @"ThreadA";
    
    [threadA start];
    
}

//耗时操作
- (void)longOperation:(id)obj
{
    for (int i = 0 ; i < 10 ; i ++) {
        
//        if (i % 2 == 0) {
            //线程休眠
//            + (void)sleepUntilDate:(NSDate *)date;休眠到某一个时间点
//            + (void)sleepForTimeInterval:(NSTimeInterval)ti;休眠多久
//           NSDate *date1 = [NSDate dateWithTimeIntervalSinceNow:2];
//            [NSThread sleepForTimeInterval:2];
//            [NSThread sleepUntilDate:date1];
//        }
        NSLog(@"当前线程---%@---%d--%@",[NSThread currentThread],i,obj);
        
//        if (i == 5) {
//            [NSThread exit];
//        }
        
        
        
    }
    
//    [self test];//在当前线程中调用
    
    [self performSelectorOnMainThread:@selector(test) withObject:self waitUntilDone:YES];
//    self performSelectorOnMainThread:<#(nonnull SEL)#> withObject:<#(nullable id)#> waitUntilDone:<#(BOOL)#> modes:<#(nullable NSArray<NSString *> *)#>
    
}

- (void)test {

    NSLog(@"%s 当前线程---%@",__FUNCTION__,[NSThread currentThread]);

}

//1.注意，任何的UI操作必须在主线程中进行。
//2.应用程序的资源分配是以进程为单位
@end