IOS多线程

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NSThread 类线程类

#pragma mark - snippet代码段

-(void)snippet

{

// NSThread类线程类

NSThread *current = [NSThreadcurrentThread];

NSLog(@"snippet's thread : %@",current);

//判断当前的线程是否为主线程

BOOL result = [NSThreadisMainThread];

NSLog(@"snippet is mainThread ? : %d",result);

//获取主线程

NSThread *mainThread = [NSThreadmainThread];

NSLog(@"当前的主线程：%@",mainThread);

//让线程延迟几秒在运行

[NSThread sleepForTimeInterval:3];

long a =0;

for (long i=0 ; i <10000000; i++) {

a+=i;

}

NSLog(@"a = %ld",a);

}

#pragma mark - 知识点1 多线程方法1:NSObject方法

- (IBAction)sender:(id)sender

{

NSLog(@"NSObject Thread: %@",[NSThreadcurrentThread]);

NSLog(@"NSObject isMainThread ? :%d",[NSThreadisMainThread]);

//使用NSObject方法，将执行的代码放在后台线程运行

//即一个子线程中

[selfperformSelectorInBackground:@selector(snippet)withObject:nil];

}

#pragma mark - 知识点2 多线程方法2：

- (IBAction)sender2:(id)sender

{

// NSThread线程类一个对象相当于一个线程

NSThread *thread1 = [[NSThreadalloc] initWithTarget:selfselector:@selector(snippet)object:nil];

//设置线程名字

thread1.name =@"aaaa";

//开始

[thread1 start];

[thread1 release];

//sender2方法2

[NSThreaddetachNewThreadSelector:@selector(snippet)toTarget:selfwithObject:nil];

}

#pragma mark - 知识点3 多线程方法3

- (IBAction)NSOperation:(id)sender

{

// NSOperation类，它是一个基类，不能直接创建对象，用它的子类创建对象，用它的子类和系统推荐的两个类创建对象

//它的子类对象，相当于一个任务（要执行的代码段）

//它的原理：将任务放入当前线程中执行

// 1自定义一个NSOperation 子类：MyOperation

MyOperation *op1 = [[MyOperationalloc] init];

MyOperation *op2 = [[MyOperationalloc] init];

MyOperation *op3 = [[MyOperationalloc] init];

[op1 start];

[op2 start];

[op3 start];

// 2系统推荐的子类

NSInvocationOperation *invocation = [[NSInvocationOperationalloc] initWithTarget:selfselector:@selector(snippet)object:nil];

[invocation start];

NSBlockOperation *blockOperation = [NSBlockOperationblockOperationWithBlock:^{

[selfsnippet];

}];

[blockOperation start];

}

#pragma mark ** NSOperationQueue实现多线程

- (IBAction)NSOperationQueue:(id)sender

{

// NSOperationQueue类任务队列

//原理：有个线程池负责把任务分配给线程，当线程执行完之后，回到线程池，等待下次新任务

NSOperationQueue *queue = [[NSOperationQueuealloc] init];

//设置最大并发数

queue.maxConcurrentOperationCount =2;

//队列中添加Operation（任务）

MyOperation *op1 = [[MyOperationalloc] init];

MyOperation *op2 = [[MyOperationalloc] init];

MyOperation *op3 = [[MyOperationalloc] init];

MyOperation *op4 = [[MyOperationalloc] init];

[queue addOperation:op1];

[queue addOperation:op2];

[queue addOperation:op3];

[queue addOperation:op4];

[queue addOperationWithBlock:^{

[selfsnippet];

}];

[queue addOperationWithBlock:^{

[selfsnippet];

}];

}

#pragma mark - 重点

#pragma mark - 知识点4 多线程方法4 GCD

- (IBAction)GCD:(id)sender

{

// GCD:大调度中心

//函数级别，效率高，推荐使用

//原理：有一个队列，队列中是代码段任务（任务的创建使用block或者函数）

//队列，可以自定义队列，也可以使用系统队列。

#if 0//自定义创建队列

// 1创建一个串行调度队列, 串行即：任务一个一个执行

dispatch_queue_t myQueue = dispatch_queue_create("com.myQueue.www", DISPATCH_QUEUE_SERIAL);

// 2调用队列中添加任务

dispatch_async(myQueue, ^{

[self snippet];

});

dispatch_async(myQueue, ^{

[self snippet];

});

dispatch_async(myQueue, ^{

[self snippet];

});

#endif

#if 0//创建自定义并发调度队列

dispatch_queue_t myConQueue = dispatch_queue_create("com.myConQuene", DISPATCH_QUEUE_CONCURRENT);

dispatch_async(myConQueue, ^{

[self snippet];

});

dispatch_async(myConQueue, ^{

[self snippet];

});

dispatch_async(myConQueue, ^{

[self snippet];

});

dispatch_async(myConQueue, ^{

[self snippet];

});

dispatch_async(myConQueue, ^{

[self snippet];

});

#endif

#pragma mark ** 系统队列

#if 0// 系统队列

//系统有一个串行队列：main 即主线程

//有4个并发队列

dispatch_queue_t mainQueue = dispatch_get_main_queue();

//向调度队列添加任务

dispatch_async(mainQueue, ^{

[self snippet];

});

dispatch_async(mainQueue, ^{

[self snippet];

});

dispatch_async(mainQueue, ^{

[self snippet];

});

#endif

#if 0

//体统的并发队列

dispatch_queue_t global = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0);

//调度队列添加任务

dispatch_async(mainQueue, ^{

[self snippet];

});

dispatch_async(mainQueue, ^{

[self snippet];

});

dispatch_async(mainQueue, ^{

[self snippet];

});

dispatch_async(mainQueue, ^{

[self snippet];

});

#endif

#pragma mark ** 重点 GCD使用

//子线程负责数据的加载

//主线程负责刷新等操作

dispatch_queue_t global =dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0);

dispatch_async(global, ^{

NSString *str =@"http://e.hiphotos.baidu.com/image/pic/item/42a98226cffc1e1786934a384890f603738de98f.jpg";

NSURL *url = [NSURLURLWithString:str];

NSData *data = [NSDatadataWithContentsOfURL:url];

UIImage *image = [UIImageimageWithData:data];

/*回到主线程队列,添加任务(刷新任务) */

dispatch_async(dispatch_get_main_queue(), ^{

self.imageview.image = image;

});

}

#pragma mark - 知识点5 重点 GCD创建单例

+(instancetype)shareViewController

{

staticViewController *vc = nil;

staticdispatch_once_t onceToken;

dispatch_once(&onceToken, ^{

vc = [[ViewControlleralloc] init];

});

return vc;

}

- (void)dealloc {

[_imageviewrelease];

[superdealloc];

}

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