1.概念说明
NSOperation的作⽤：配合使用NSOperation和NSOperationQueue也能实现多线程编程
NSOperation和NSOperationQueue实现多线程的具体步骤：
（1）先将需要执行的操作封装到一个NSOperation对象中
（2）然后将NSOperation对象添加到NSOperationQueue中
（3）系统会⾃动将NSOperationQueue中的NSOperation取出来
（4）将取出的NSOperation封装的操作放到⼀条新线程中执⾏
2.NSOperation的子类
NSOperation是个抽象类,并不具备封装操作的能力,必须使⽤它的子类
使用NSOperation⼦类的方式有3种：
（1）NSInvocationOperation
（2）NSBlockOperation
（3）自定义子类继承NSOperation,实现内部相应的⽅法
2、具体实现
- (IBAction)OnBlockOptClick:(UIButton *)sender {
NSBlockOperation *operation = [[NSBlockOperation alloc] init];
[operation addExecutionBlock:^{
NSLog(@"NSBlockOperation------下载图片1---%@", [NSThread currentThread]);
}];
[operation addExecutionBlock:^{
NSLog(@"NSBlockOperation------下载图片2---%@", [NSThread currentThread]);
}];
[operation addExecutionBlock:^{
NSLog(@"NSBlockOperation------下载图片3---%@", [NSThread currentThread]);
}];
[operation start]; //若operation的Block个数多于一个，会自动开启新的线程实现并发
}
- (IBAction)OnInvocationOptClick:(UIButton *)sender {
// 1.创建操作对象, 封装要执行的任务
NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(download) object:nil];
// 2.执行操作(默认情况下, 如果操作没有放到队列queue中, 都是同步执行)
[operation start];
}
- (IBAction)OnQueueClick:(UIButton *)sender {
// 1.封装操作
NSInvocationOperation *operation1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(download) object:nil];
// operation1.queuePriority = NSOperationQueuePriorityHigh
NSInvocationOperation *operation2 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(run) object:nil];
NSBlockOperation *operation3 = [NSBlockOperation blockOperationWithBlock:^{
for (int i = 0; i<10; i++) {
NSLog(@"NSBlockOperation------下载图片---%@", [NSThread currentThread]);
[NSThread sleepForTimeInterval:0.1];
}
}];
// 2.创建队列
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 2; // 2 ~ 3为宜
// 通过设置依赖来确定operation执行的顺序
[operation2 addDependency:operation3];
[operation3 addDependency:operation1];
// 3.添加操作到队列中(自动执行操作, 自动开启线程)
[queue addOperation:operation1];
[queue addOperation:operation2];
[queue addOperation:operation3];
[queue addOperationWithBlock:^{
NSLog(@"NSBlockOperation------下载图片3---%@", [NSThread currentThread]);
}];
// [queue setSuspended:YES];
}
- (IBAction)OnHDClick:(UIButton *)sender {
NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
for (int i = 0; i<10; i++) {
NSLog(@"NSBlockOperation------下载图片---%@", [NSThread currentThread]);
}
}];
operation.completionBlock = ^{
// ...下载完图片后想做事情
NSLog(@"NSBlockOperation------下载图片完毕---%@", [NSThread currentThread]);
};
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperation:operation];
}
- (void)download
{
NSLog(@"让我来下载。。。");
}