iOS中多线程实现方案

iOS中多线程实现方案

GCD

NSOperation

GCD的使用方法

队列的类型

GCD执行任务的常用函数

同步和异步的区别

GCD执行任务的多种情况实例

使用异步方式创建任务，将任务放入串行队列中

- (void)asyncSerial{
//创建串行队列
dispatch_queue_t queue = dispatch_queue_create("lcs", DISPATCH_QUEUE_SERIAL);

NSLog(@" %@", [NSThread currentThread]);

dispatch_async(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_async(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_async(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
}

运行结果(开启一个新线程，串行执行)

2016-04-09 13:35:30.409 GCD的使用[1473:29019]  <NSThread: 0x7f92fad07770>{number = 1, name = main}
2016-04-09 13:35:30.410 GCD的使用[1473:29101]  <NSThread: 0x7f92fae03bf0>{number = 2, name = (null)} =======  0
2016-04-09 13:35:30.410 GCD的使用[1473:29101]  <NSThread: 0x7f92fae03bf0>{number = 2, name = (null)} =======  1
2016-04-09 13:35:30.410 GCD的使用[1473:29101]  <NSThread: 0x7f92fae03bf0>{number = 2, name = (null)} =======  0
2016-04-09 13:35:30.410 GCD的使用[1473:29101]  <NSThread: 0x7f92fae03bf0>{number = 2, name = (null)} =======  1
2016-04-09 13:35:30.411 GCD的使用[1473:29101]  <NSThread: 0x7f92fae03bf0>{number = 2, name = (null)} =======  0
2016-04-09 13:35:30.411 GCD的使用[1473:29101]  <NSThread: 0x7f92fae03bf0>{number = 2, name = (null)} =======  1

使用异步方式创建任务，将任务放入主队列中

- (void)asyncMainQueue{

//主队列 (加入到主队列中的任务，都在主线程执行)
dispatch_queue_t mainQueue = dispatch_get_main_queue();

NSLog(@" %@", [NSThread currentThread]);

dispatch_async(mainQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_async(mainQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_async(mainQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
}

运行结果(在主队列串行执行)

使用异步方式创建任务，将任务放入并行队列中

- (void)asyncConcurrent{

//自己创建并发队列
dispatch_queue_t queue = dispatch_queue_create("lcs", DISPATCH_QUEUE_CONCURRENT);

//全局并发队列
dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

NSLog(@" %@", [NSThread currentThread]);

dispatch_async(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_async(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_async(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});

//async 异步函数，会等当前函数执行完后在开线程
NSLog(@"asyncConcurrent");
}

运行结果(开启多个线程并行执行)

使用同步方式创建任务，将任务放入串行队列中

- (void)syncSerial{

//自己创建并发队列
dispatch_queue_t queue = dispatch_queue_create("lcs", DISPATCH_QUEUE_SERIAL);

NSLog(@" %@", [NSThread currentThread]);

dispatch_sync(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_sync(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_sync(queue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});

//sync  同步函数，会立刻加入到队列中执行
NSLog(@"asyncConcurrent");

}

运行结果(在当前线程串行执行)

使用同步方式创建任务，将任务放入并行队列中

- (void)syncConcurrent{

//全局并发队列
dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
NSLog(@" %@", [NSThread currentThread]);

dispatch_sync(globalQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_sync(globalQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_sync(globalQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
//sync  同步函数，会立刻加入到队列中执行
NSLog(@"asyncConcurrent");
}

运行结果同上一种情况

使用同步方式创建任务，将任务放入主队列中

- (void)syncMainQueue{

//主队列 (加入到主线程中的任务，都在主线程执行)
dispatch_queue_t mainQueue = dispatch_get_main_queue();

NSLog(@" %@", [NSThread currentThread]);

dispatch_sync(mainQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_sync(mainQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
dispatch_sync(mainQueue, ^{
for (NSInteger i = 0; i < 2; i++) {
NSLog(@" %@ =======  %ld", [NSThread currentThread], i);
}
});
}

运行结果(任务加入主队列造成互相等待，导致死锁)

GCD多线程总结

NSOperation的使用方法

队列的类型

创建任务

- (void)viewDidLoad {
[super viewDidLoad];

//创建队列
_queue = [[NSOperationQueue alloc] init];

//设置最大并发数,设置为1，则该队列就是串行队列
_queue.maxConcurrentOperationCount = 3;
}

- (void)createOperation{
//创建任务
//方式一
NSInvocationOperation *op1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(run) object:nil];

//方式二
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"messionBlock %@", [NSThread currentThread]);
}];
//添加额外的block
[op2 addExecutionBlock:^{
NSLog(@"messionExecution %@", [NSThread currentThread]);
}];

//方式三：自定义:(实现类的main方法)
CSOperation *op3 = [[CSOperation alloc] init];

//加入队列
[_queue addOperation:op1]; //内部调用 [op1 start]
[_queue addOperation:op2];
[_queue addOperation:op3];
[_queue addOperationWithBlock:^{
NSLog(@"messionOperationWithBlock %@", [NSThread currentThread]);
}];
}

- (void)run{
for(int i = 0;i < 10; i++){
NSLog(@"%d messionInvocation %@", i, [NSThread currentThread]);
}

}

运行结果(开启多个线程，并行执行)

设置任务之间的依赖，保证执行顺序(依赖设置可以跨队列操作)

- (void)addDependency{

NSBlockOperation *b1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"b1");
}];

NSBlockOperation *b2 = [NSBlockOperation blockOperationWithBlock:^{
for(int i = 0; i < 2; i++){
NSLog(@"b2");
}
}];
NSBlockOperation *b3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"b3");
}];

//监听线程执行完毕
b3.completionBlock = ^{
NSLog(@"b3 执行完毕 ---%@", [NSThread currentThread]);
};

//b3依赖于b1 b2
[b3 addDependency:b1];
[b3 addDependency:b2];

[_queue addOperation:b1];
[_queue addOperation:b2];
[_queue addOperation:b3];

}

运行结果(b3等待b1，b2任务执行完后再执行)