1.最大并发数:
- (NSInteger)maxConcurrentOperationCount;
- (void)setMaxConcurrentOperationCount:(NSInteger)cnt;
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
queue.maxConcurrentOperationCount = 3;
注:系统一般会根据内存大小自动设置并发数目,也可以自己设定,但是不要乱设,一般不要超过5个。
2.暂停和取消
(1)取消队列的所有操作
- (void)cancelAllOperations;
提⽰:也可以调用NSOperation的- (void)cancel⽅法取消单个操作
(2)暂停和恢复队列
- (void)setSuspended:(BOOL)b; // YES代表暂停队列,NO代表恢复队列
- (BOOL)isSuspended; //当前状态
3.操作优先级 : 设置NSOPeration的优先级,可以改变在NSOPerationQueue中的执行优先级
[operation2 setQueuePriority:NSOperationQueuePriorityNormal]; //设置优先级
NSOperationQueuePriority priority = operation2.queuePriority; //获去操作的优先级
4.操作依赖
有两个操作,operationA:买饭和operationB:吃饭,必须要先买饭,然后再吃饭。操作B:吃饭 必须等到操作A:买饭 的操作完成后才能执行。这就是依赖关系。
在NSOPeration中描述依赖用:[operationB addDependency:operationA];
- (void)viewDidLoad {
[super viewDidLoad];
NSInvocationOperation *operationA = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(testAction) object:nil];
NSInvocationOperation *operationB = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(testAction1) object:nil];
[operationB addDependency:operationA];
//定义队列
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
//将操作添加到队列
[queue addOperation:operationA];
[queue addOperation:operationB];
}
-(void)testAction
{
for (int i = 0; i < 5; i ++) {
NSLog(@"给五个人买饭带回宿舍----%@",[NSThread currentThread]);
}
}
-(void)testAction1
{
for (int i = 0; i < 5; i ++) {
NSLog(@"五个人开始吃饭----%@",[NSThread currentThread]);
}
}
2017-06-18 11:33:26.765 demo[17639:3076261] 给五个人买饭带回宿舍----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.766 demo[17639:3076261] 给五个人买饭带回宿舍----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.767 demo[17639:3076261] 给五个人买饭带回宿舍----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.768 demo[17639:3076261] 给五个人买饭带回宿舍----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.769 demo[17639:3076261] 给五个人买饭带回宿舍----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.770 demo[17639:3076261] 五个人开始吃饭----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.776 demo[17639:3076261] 五个人开始吃饭----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.777 demo[17639:3076261] 五个人开始吃饭----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.781 demo[17639:3076261] 五个人开始吃饭----<NSThread: 0x600000267b40>{number = 3, name = (null)}
2017-06-18 11:33:26.782 demo[17639:3076261] 五个人开始吃饭----<NSThread: 0x600000267b40>{number = 3, name = (null)}
注:用for循环更能看出操作的执行顺序。
5.操作的监听
有时候需要执行完一个操作再执行另个操作,可以将这两个操作写在一起,但是当代码很多的时候,会造成阅读性不强。
NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
for (int i = 0; i < 5; i ++) {
NSLog(@"给五个人买饭带回宿舍----%@",[NSThread currentThread]);
}
for (int i = 0; i < 5; i ++) {
NSLog(@"五个人开始吃饭----%@",[NSThread currentThread]);
}
}];
//定义队列
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
//将操作添加到队列
[queue addOperation:operation];
也可以分开写:
NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
for (int i = 0; i < 5; i ++) {
NSLog(@"给五个人买饭带回宿舍----%@",[NSThread currentThread]);
}
}];
operation.completionBlock = ^{
for (int i = 0; i < 5; i ++) {
NSLog(@"五个人开始吃饭----%@",[NSThread currentThread]);
}
};
//定义队列
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
//将操作添加到队列
[queue addOperation:operation];
2017-06-18 11:41:21.883 demo[17675:3084893] 给五个人买饭带回宿舍----<NSThread: 0x600000071200>{number = 3, name = (null)}
2017-06-18 11:41:21.885 demo[17675:3084893] 给五个人买饭带回宿舍----<NSThread: 0x600000071200>{number = 3, name = (null)}
2017-06-18 11:41:21.886 demo[17675:3084893] 给五个人买饭带回宿舍----<NSThread: 0x600000071200>{number = 3, name = (null)}
2017-06-18 11:41:21.888 demo[17675:3084893] 给五个人买饭带回宿舍----<NSThread: 0x600000071200>{number = 3, name = (null)}
2017-06-18 11:41:21.888 demo[17675:3084893] 给五个人买饭带回宿舍----<NSThread: 0x600000071200>{number = 3, name = (null)}
2017-06-18 11:41:21.894 demo[17675:3084895] 五个人开始吃饭----<NSThread: 0x60800006c600>{number = 4, name = (null)}
2017-06-18 11:41:21.895 demo[17675:3084895] 五个人开始吃饭----<NSThread: 0x60800006c600>{number = 4, name = (null)}
2017-06-18 11:41:21.896 demo[17675:3084895] 五个人开始吃饭----<NSThread: 0x60800006c600>{number = 4, name = (null)}
2017-06-18 11:41:21.897 demo[17675:3084895] 五个人开始吃饭----<NSThread: 0x60800006c600>{number = 4, name = (null)}
2017-06-18 11:41:21.898 demo[17675:3084895] 五个人开始吃饭----<NSThread: 0x60800006c600>{number = 4, name = (null)}
注:可以看出当买饭的操作完成后,开启一个新线程执行吃饭操作。