NSOperation的作?：配合使用NSOperation和NSOperationQueue也能實現多線程編程
NSOperation和NSOperationQueue實現多線程的具體步驟：
1）先將需要履行的操作封裝到1個NSOperation對象中
2）然后將NSOperation對象添加到NSOperationQueue中
3）系統會?動將NSOperationQueue中的NSOperation取出來
4）將取出的NSOperation封裝的操作放到?條新線程中執?
NSOperation是個抽象類,其實不具有封裝操作的能力,必須使?它的子類
使用NSOperation?類的方式有3種：
1）NSInvocationOperation
2）NSBlockOperation
3）自定義子類繼承NSOperation,實現內部相應的?法
NSInvocationOperation 開啟任務方法
//用 NSInvocationOperation 創建線程
NSInvocationOperation *invocation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(download:) object:@"NSInvocationOperation"];
//在當前線程中同步履行
[invocation start];
- (void)download:(NSString *)url{
NSLog(@"%@ --- %@", [NSThread currentThread], url);
}
將創建的任務添加到隊列中,異步履行
- (void)invocationOperation{
//用 NSInvocationOperation 創建線程
NSInvocationOperation *invocation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(download:) object:@"NSInvocationOperation"];
//創建全局隊列(實現異步并發履行)
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
//從對列中取出任務履行(異步)
[queue addOperation:invocation];
}
- (void)download:(NSString *)url{
NSLog(@"%@ --- %@", [NSThread currentThread], url);
}
注意:操作對象默許在主線程中履行，只有添加到隊列中才會開啟新的線程。即默許情況下，如果操作沒有放到隊列中queue中，都是同步履行。只有將NSOperation放到1個NSOperationQueue中,才會異步履行操作
NSBlockOperation 開啟任務的方法
NSBlockOperation 添加任務
- (void)blockOperation2{
//創建任務
NSBlockOperation *operation1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下載圖片1 --- %@", [NSThread currentThread]);
}];
[operation1 start];
}
注意:只要NSBlockOperation封裝的操作數 > 1,就會異步履行操作
- (void)blockOperation2{
//注意:只要NSBlockOperation封裝的操作數 > 1,就會異步履行操作
//創建任務
NSBlockOperation *operation1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下載圖片1 --- %@", [NSThread currentThread]);
}];
[operation1 addExecutionBlock:^{
NSLog(@"下載圖片2 --- %@", [NSThread currentThread]);
}];
[operation1 addExecutionBlock:^{
NSLog(@"下載圖片3 --- %@", [NSThread currentThread]);
}];
[operation1 start];
}
NSOperationQueue
NSOperationQueue的作?：NSOperation可以調?start?法來執?任務,但默許是同步履行的
如果將NSOperation添加到NSOperationQueue(操作隊列)中,系統會自動異步履行NSOperation中的操作
添加操作到NSOperationQueue中，自動履行操作，自動開啟線程
獲得 NSOperationQueue 隊列:
NSOperationQueue *queue = [[NSOperationQueue alloc] init];//并發隊列
NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];//主隊列添加任務有兩個方法:
- (void)addOperation:(NSOperation *)op;
- (void)addOperationWithBlock:(void (^)(void))block; 實例代碼
- (void)blockOperation{
//創建全局隊列(實現異步并發履行)
NSOperationQueue *queue = [[NSOperationQueue alloc] init];//并發隊列
//NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];//主隊列
//創建任務
NSBlockOperation *operation1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下載圖片1 --- %@", [NSThread currentThread]);
}];
NSBlockOperation *operation2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下載圖片2 --- %@", [NSThread currentThread]);
}];
NSBlockOperation *operation3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下載圖片3 --- %@", [NSThread currentThread]);
}];
NSBlockOperation *operation4 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下載圖片4 --- %@", [NSThread currentThread]);
}];
NSBlockOperation *operation5 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下載圖片5 --- %@", [NSThread currentThread]);
}];
//將任務添加到隊列中
[queue addOperation:operation1];
[queue addOperation:operation2];
[queue addOperation:operation3];
[queue addOperation:operation4];
[queue addOperation:operation5];
}
- (void)queueAddBlock{
//創建全局隊列(實現異步并發履行)
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
//直接向隊列中添加任務
[queue addOperationWithBlock:^{
NSLog(@"下載圖片1 --- %@", [NSThread currentThread]);
}];
[queue addOperationWithBlock:^{
NSLog(@"下載圖片2 --- %@", [NSThread currentThread]);
}];
[queue addOperationWithBlock:^{
NSLog(@"下載圖片3 --- %@", [NSThread currentThread]);
}];
[queue addOperationWithBlock:^{
NSLog(@"下載圖片4 --- %@", [NSThread currentThread]);
}];
[queue addOperationWithBlock:^{
NSLog(@"下載圖片5 --- %@", [NSThread currentThread]);
}];
}
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