NSOperation 抽象类NSOperation是一个抽象类，不能直接使用抽象类的用处是定义子类共有的属性和方法在苹果的头文件中，有些抽象类和子类的定义是在同一个头文件中的子类：NSInvocationOperation(调用)NSBlockOperation(块)NSOperationQueue队列已经学习过的抽象类UIGestureRecognizerCAAnimationCAPRopertyAnimation基本演练NSInvocationOperationstartstart方法 会在当前线程执行@selector方法- (void)opDemo1 {
NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@"Invocation"];
// start方法 会在当前线程执行 @selector 方法
[op start];
}
- (void)downloadImage:(id)obj {
NSLog(@"%@ %@", [NSThread currentThread], obj);
}
添加到队列将操作添加到队列，会异步执行selector方法- (void)opDemo2 {
NSOperationQueue *q = [[NSOperationQueue alloc] init];
NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@"queue"];
[q addOperation:op];
}
添加多个操作- (void)opDemo3 {
NSOperationQueue *q = [[NSOperationQueue alloc] init];
for (int i = 0; i < 10; ++i) {
NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@(i)];
[q addOperation:op];
}
}
执行效果：会开启多条线程，而且不是顺序执行。与GCD中并发队列&异步执行效果一样！
结论，在 NSOperation 中：
操作 -> 异步执行的任务队列 -> 全局队列NSBlockOperation- (void)opDemo4 {
NSOperationQueue *q = [[NSOperationQueue alloc] init];
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@", [NSThread currentThread]);
}];
[q addOperation:op];
}
使用 block 来定义操作，所有的代码写在一起，更简单，便于维护！
更简单的，直接添加 Block- (void)opDemo5 {
NSOperationQueue *q = [[NSOperationQueue alloc] init];
for (int i = 0; i < 10; ++i) {
[q addOperationWithBlock:^{
NSLog(@"%@ %d", [NSThread currentThread], i);
}];
}
}
向队列中添加不同的操作- (void)opDemo5 {
NSOperationQueue *q = [[NSOperationQueue alloc] init];
for (int i = 0; i < 10; ++i) {
[q addOperationWithBlock:^{
NSLog(@"%@ %d", [NSThread currentThread], i);
}];
}
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"block %@", [NSThread currentThread]);
}];
[q addOperation:op1];
NSInvocationOperation *op2 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadImage:) object:@"invocation"];
[q addOperation:op2];
}
可以向NSOperationQueue中添加任意NSOperation的子类线程间通讯- (void)opDemo6 {
NSOperationQueue *q = [[NSOperationQueue alloc] init];
[q addOperationWithBlock:^{
NSLog(@"耗时操作 %@", [NSThread currentThread]);
// 主线程更新 UI
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
NSLog(@"更新 UI %@", [NSThread currentThread]);
}];
}];
}
高级演练全局队列/// 全局操作队列，统一管理所有的异步操作
@property (nonatomic, strong) NSOperationQueue *queue;
- (NSOperationQueue *)queue {
if (_queue == nil) {
_queue = [[NSOperationQueue alloc] init];
}
return _queue;
}
最大并发操作数/// MARK: - 最大并发操作数
- (void)opDemo1 {
// 设置同时并发操作数
self.queue.maxConcurrentOperationCount = 2;
NSLog(@"start");
for (int i = 0; i < 10; ++i) {
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
[NSThread sleepForTimeInterval:1.0];
NSLog(@"%@ %d", [NSThread currentThread], i);
}];
[self.queue addOperation:op];
}
}
暂停 & 继续/// MARK: - 暂停 & 继续
- (IBAction)pauseAndResume {
if (self.queue.operationCount == 0) {
NSLog(@"没有操作");
return;
}
// 暂停或者继续
self.queue.suspended = !self.queue.isSuspended;
if (self.queue.isSuspended) {
NSLog(@"暂停 %tu", self.queue.operationCount);
} else {
NSLog(@"继续 %tu", self.queue.operationCount);
}
}
队列挂起，当前没有完成的操作，是包含在队列的操作数中的队列挂起，不会影响已经执行操作的执行状态对列一旦被挂起，再添加的操作不会被调度取消全部操作/// MARK: - 取消所有操作
- (IBAction)cancelAll {
if (self.queue.operationCount == 0) {
NSLog(@"没有操作");
return;
}
// 取消对列中的所有操作，同样不会影响到正在执行中的操作！
[self.queue cancelAllOperations];
NSLog(@"取消全部操作 %tu", self.queue.operationCount);
}
取消队列中所有的操作不会取消正在执行中的操作不会影响队列的挂起状态依赖关系/// MARK: - 依赖关系
- (void)dependency {
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"登录 %@", [NSThread currentThread]);
}];
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"付费 %@", [NSThread currentThread]);
}];
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下载 %@", [NSThread currentThread]);
}];
NSBlockOperation *op4 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"通知用户 %@", [NSThread currentThread]);
}];
[op2 addDependency:op1];
[op3 addDependency:op2];
[op4 addDependency:op3];
// 注意不要循环依赖
// [op1 addDependency:op4];
[self.queue addOperations:@[op1, op2, op3] waitUntilFinished:NO];
[[NSOperationQueue mainQueue] addOperation:op4];
NSLog(@"come here");
}