iOS多線程技術(shù)

iOS有三種多線程編程技術(shù):

• NSThread
• NSOperation
• GCD

它們的抽象程度由低到高,越高的使用起來越簡單。

NSThread

顯示調(diào)用NSThread類

• 類方法

  [NSThread detachNewThreadSelector:@selector(doSomething:) toTarget:self withObject:@"hi"];

• 實(shí)例方法

  NSThread *thread = [[NSThread alloc]initWithTarget:self selector:@selector(doSomething:) object:@"hi"]; [thread start];

隱式調(diào)用

• 開啟后臺線程

  [self performSelectorInBackground:@selector(doSomething:) withObject:@"hi"];

• 在主線程中運(yùn)行

  [self performSelectorOnMainThread:@selector(doSomething:) withObject:@"hi" waitUntilDone:YES];

• 在指定線程中執(zhí)行,但該線程必須具備run loop

  [self performSelector::@selector(doSomething:) onThread:thread withObject:@"hi" waitUntilDone:YES];

常見NSThread的方法

+ (NSThread *)currentThread; //獲得當(dāng)前線程 + (void)sleepForTimeInterval:(NSTimeInterval)ti; //線程休眠 + (NSThread *)mainThread; //主線程,亦即UI線程了 - (BOOL)isMainThread; + (BOOL)isMainThread; //當(dāng)前線程是否主線程 - (BOOL)isExecuting; //線程是否正在運(yùn)行 - (BOOL)isFinished; //線程是否已結(jié)束

NSOperation

• NSInvocationOperation

// 創(chuàng)建一個隊(duì)列NSOperationQueue queue = [[NSOperationQueue alloc]init];// 創(chuàng)建子任務(wù), 定義子任務(wù)必須是NSOperation的子類NSInvocationOperation operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(doSomething:) object:@"hi"];// 當(dāng)把任務(wù)添加到隊(duì)列后, 自動開啟線程,[queue addOperation:operation];

• NSBlockOperation

// 創(chuàng)建一個隊(duì)列NSOperationQueue queue = [[NSOperationQueue alloc]init];// 創(chuàng)建NSBlockOperaion對象NSBlockOperation operation = [NSBlockOperation blockOperationWithBlock:^{[self doSomething];}];// 加入隊(duì)列[queque addOperation:operation];

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