都是些基本的东西，但是温故而知新哈
iOS中有三种多线程编程的技术分别是：
-
NSThread
-
NSOperation（NSOperation 和 NSOperationQueue）
-
GCD
-
NSThread
优点：NSThread 比其他两个轻量级。
缺点：需要自己管理线程的生命周期，线程同步对数据的加锁会有一定的系统开销。
// 第一种 直接创建新线程并且开始运行线程
[NSThread detachNewThreadSelector:@selector(myThread:) toTarget:self withObject:nil];
// 第二种 先创建新线程，再运行操作，在运行操作前可以设置线程优先级等相关信息
NSThread *myThread = [[NSThread alloc] initWithTarget:self selector:@selector(myThread:) object:nil];
[myThread start];
// 第三种 隐式创建
[self performSelectorInBackground:@selector(myThread:) withObject:nil];
// 使用NSThread写一个经典的卖票的例子来讲线程同步
- (void)syncThread {
// 初始化总票数
self.tickes = 100;
// 初始化锁对象
self.myLock = [[NSLock alloc] init];
// 创建两个线程，模拟网上售票和站台售票
NSThread *onlineThread = [[NSThread alloc] initWithTarget:self selector:@selector(sellTickes) object:nil];
onlineThread.name = @"网上售票口";
[onlineThread start];
NSThread *stationThread = [[NSThread alloc] initWithTarget:self selector:@selector(sellTickes) object:nil];
stationThread.name = @"站点售票口";
[stationThread start];
}
- (void)sellTickes {
while (true) {
// 加锁
[self.myLock lock];
// 模拟网络堵塞
[NSThread sleepForTimeInterval:1];
if (self.tickes > 0) {
self.tickes -= 1;
NSLog(@"当前售票口是:%@, 余票%d张。", [[NSThread currentThread] name], self.tickes);
}else{
NSLog(@"亲，你来晚了，票卖完了！");
break;
}
// 解锁
[self.myLock unlock];
}
}
- NSOperation的使用方法有两种
一种是使用定义好的两个子类： NSInvocationOperation 和 NSBlockOperation
第二种是继承NSOperation
- (void)testNSOperation {
// 使用定义好的两个子类
NSInvocationOperation *operation1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(test) object:nil];
operation1.name = @"operation1";
NSBlockOperation *blockOperation = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"blockOperation %@", [NSThread currentThread]);
}];
blockOperation.name = @"blockOperation";
// 把NSOperation子类放入队列中去
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperation:operation1];
[queue addOperation:blockOperation];
queue.maxConcurrentOperationCount = 2; // 最大并发数
}
- (void)test {
NSLog(@"invocationOperation %@", [NSThread currentThread]);
}
- GCD
GCD的底层依然使用线程实现的，可以让程序员不用关注细节
GCD中的队列称为dispath queue，有两种一是串行队列，一是并行队列。
执行的时候，又分为同步（不开子线程）和异步（开子线程）
/** 异步-全局并发 */
- (IBAction)async1 {
// 获得全局并发队列（常用就是这个）
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
NSLog(@"1 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"2 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"3 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"4 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"5 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"6 = %@", [NSThread currentThread]);
});
/*
打印结果
2016-03-08 13:26:13.109 NSThreadDemo[38192:1073138] 2 = <NSThread: 0x7fecf8da1cb0>{number = 3, name = (null)}
2016-03-08 13:26:13.109 NSThreadDemo[38192:1073139] 3 = <NSThread: 0x7fecf8e30fe0>{number = 4, name = (null)}
2016-03-08 13:26:13.109 NSThreadDemo[38192:1073140] 1 = <NSThread: 0x7fecf8f19840>{number = 2, name = (null)}
2016-03-08 13:26:13.109 NSThreadDemo[38192:1073586] 5 = <NSThread: 0x7fecf8d04cd0>{number = 6, name = (null)}
2016-03-08 13:26:13.109 NSThreadDemo[38192:1073585] 4 = <NSThread: 0x7fecf8f06c00>{number = 5, name = (null)}
2016-03-08 13:26:13.110 NSThreadDemo[38192:1073138] 6 = <NSThread: 0x7fecf8da1cb0>{number = 3, name = (null)}
*/
}
/** 异步-串行 */
- (IBAction)async2 {
// 自己创建一个队列
dispatch_queue_t queue = dispatch_queue_create("liyang", NULL);
dispatch_async(queue, ^{
NSLog(@"1 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"2 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"3 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"4 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"5 = %@", [NSThread currentThread]);
});
dispatch_async(queue, ^{
NSLog(@"6 = %@", [NSThread currentThread]);
});
/*
打印结果
2016-03-08 13:26:42.443 NSThreadDemo[38192:1078469] 1 = <NSThread: 0x7fecf8e1ef20>{number = 7, name = (null)}
2016-03-08 13:26:42.443 NSThreadDemo[38192:1078469] 2 = <NSThread: 0x7fecf8e1ef20>{number = 7, name = (null)}
2016-03-08 13:26:42.443 NSThreadDemo[38192:1078469] 3 = <NSThread: 0x7fecf8e1ef20>{number = 7, name = (null)}
2016-03-08 13:26:42.444 NSThreadDemo[38192:1078469] 4 = <NSThread: 0x7fecf8e1ef20>{number = 7, name = (null)}
2016-03-08 13:26:42.444 NSThreadDemo[38192:1078469] 5 = <NSThread: 0x7fecf8e1ef20>{number = 7, name = (null)}
2016-03-08 13:26:42.444 NSThreadDemo[38192:1078469] 6 = <NSThread: 0x7fecf8e1ef20>{number = 7, name = (null)}
*/
}
/** 同步-并发 */
- (IBAction)sync1 {
// 获得全局并发队列（常用就是这个）
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_sync(queue, ^{
NSLog(@"1 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"2 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"3 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"4 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"5 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"6 = %@", [NSThread currentThread]);
});
/*
打印结果
2016-03-08 13:27:37.110 NSThreadDemo[38192:1072944] 1 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:27:37.110 NSThreadDemo[38192:1072944] 2 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:27:37.110 NSThreadDemo[38192:1072944] 3 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:27:37.110 NSThreadDemo[38192:1072944] 4 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:27:37.110 NSThreadDemo[38192:1072944] 5 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:27:37.111 NSThreadDemo[38192:1072944] 6 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
*/
}
/** 同步-串行 */
- (IBAction)sync2 {
// 自己创建一个队列
dispatch_queue_t queue = dispatch_queue_create("liyang", NULL);
dispatch_sync(queue, ^{
NSLog(@"1 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"2 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"3 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"4 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"5 = %@", [NSThread currentThread]);
});
dispatch_sync(queue, ^{
NSLog(@"6 = %@", [NSThread currentThread]);
});
/*
打印结果
2016-03-08 13:28:06.597 NSThreadDemo[38192:1072944] 1 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:28:06.597 NSThreadDemo[38192:1072944] 2 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:28:06.597 NSThreadDemo[38192:1072944] 3 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:28:06.597 NSThreadDemo[38192:1072944] 4 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:28:06.597 NSThreadDemo[38192:1072944] 5 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
2016-03-08 13:28:06.597 NSThreadDemo[38192:1072944] 6 = <NSThread: 0x7fecf8e05160>{number = 1, name = main}
*/
}
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