ios多线程之NSOperation和NSOperationQueue - hshd

转自:http://www.tuicool.com/articles/NvMr2qr

NSOperation的作用配合使用NSOperation和NSOperationQueue也能实现多线程编程1、NSOperation和NSOperationQueue实现多线程的具体步骤2、先将需要执行的操作封装到一个NSOperation对象中3、然后将NSOperation对象添加到NSOperationQueue中4、系统会自动将NSOperationQueue中的NSOperation取出来5、将取出的NSOperation封装的操作放到一条新线程中执行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1、使用NSOperation子类的方式有3种2、NSInvocationOperation3、NSBlockOperation4、自定义子类继承NSOperation，实现内部相应的方法下面是DEMO@interface CZViewController ()/** NSOperation操作队列 */@property (nonatomic, strong) NSOperationQueue *queue;@end@implementation CZViewController// 将操作添加到队列即可- (NSOperationQueue *)queue{    if (!_queue) _queue = [[NSOperationQueue alloc] init];    return _queue;}- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{    [self opDemo6];}/** 暂停操作 */- (IBAction)pause{    // 1. 判断队列中是否有操作    if (self.queue.operationCount == 0) {        NSLog(@"没有操作");        return;    }        // 2. 如果没有被挂起(正在执行)，才需要暂停    // 只会挂起当前队列中还没有被调度（没有被安排到线程上工作的操作）才会被挂起    if (!self.queue.isSuspended) {        NSLog(@"暂停");        [self.queue setSuspended:YES];    } else {        NSLog(@"已经暂停");    }}/** 继续操作 */- (IBAction)resume{    // 1. 判断队列中是否有操作    if (self.queue.operationCount == 0) {        NSLog(@"没有操作");        return;    }        // 2. 如果有被挂起的操作，才需要继续(恢复)    if (self.queue.isSuspended) {        NSLog(@"继续");        [self.queue setSuspended:NO];    } else {        NSLog(@"正在执行");    }}#pragma mark - NSOperation演练/** 操作之间的依赖 */- (void)opDemo6{    NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"正在下载图书 。。。 %@", [NSThread currentThread]);    }];        NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"正在解压缩图书 。。。 %@", [NSThread currentThread]);    }];        NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"正在保存到磁盘 。。。 %@", [NSThread currentThread]);    }];        NSBlockOperation *op4 = [NSBlockOperation blockOperationWithBlock:^{        NSLog(@"更新书架（UI），提示用户可以阅读 。。。 %@", [NSThread currentThread]);    }];        // 指定操作之间的”依赖“关系，某一个操作的执行，必须等待另一个操作完成才会开始    // 依赖关系是可以跨队列指定的    [op2 addDependency:op1];    [op3 addDependency:op2];    [op4 addDependency:op3];    // *** 添加依赖的时候，注意不要出现循环依赖//    [op3 addDependency:op4];        [self.queue addOperation:op1];    [self.queue addOperation:op2];    [self.queue addOperation:op3];    // 主队列更新UI    [[NSOperationQueue mainQueue] addOperation:op4];}/** 最大并发数 */- (void)opDemo5{    // 设置队列的最大并发数，队列是负责调度操作的    /**     最大并发数的应用场景：          1> 用户在使用3G的时候          限制线程的数量，省电，省流量(省钱)     2> 用户使用WIFI的时候（局域网） 增加线程数量，提高用户的体验          maxConcurrentOperationCount 如果＝＝ 1，类似于串行队列异步方法     */    self.queue.maxConcurrentOperationCount = 1;        for (int i = 0; i < 10; i++) {        [self.queue addOperationWithBlock:^{            // 模拟休眠            [NSThread sleepForTimeInterval:1.0f];                        NSLog(@"正在下载 %@ %d", [NSThread currentThread], i);        }];    }}/** Block操作，添加执行块 */- (void)opDemo4{    // 实例化block操作    NSBlockOperation *op = [[NSBlockOperation alloc] init];        // 设置最大并发（操作）数，不会限制执行块！    self.queue.maxConcurrentOperationCount = 2;        // 添加执行块    [op addExecutionBlock:^{        NSLog(@"下载书籍1 %@", [NSThread currentThread]);    }];        // 继续添加块    [op addExecutionBlock:^{        NSLog(@"下载书籍2 %@", [NSThread currentThread]);    }];        // 继续添加块    [op addExecutionBlock:^{        NSLog(@"下载书籍3 %@", [NSThread currentThread]);    }];        // 继续添加块    [op addExecutionBlock:^{        NSLog(@"下载书籍4 %@", [NSThread currentThread]);    }];        // 继续添加块    [op addExecutionBlock:^{        NSLog(@"下载书籍5 %@", [NSThread currentThread]);    }];        // 启动操作，在主线程执行    // 如果执行块的数量超过1，就会自动进入其他线程执行(异步)    // 具体开启线程的数量，由系统决定    // 执行块的调度与操作的调度非常像//    [op start];    [self.queue addOperation:op];}/** 直接添加块操作 */- (void)opDemo3{    // 只要将操作添加到队列就会立即被调度（执行）    for (int i = 0; i < 10; i++) {        [self.queue addOperationWithBlock:^{            NSLog(@"下载开始 %@ - %@", [NSThread currentThread], @(i));        }];    }        // 向主队列中添加操作    [[NSOperationQueue mainQueue] addOperationWithBlock:^{        NSLog(@"下载开始 %@ - %@", [NSThread currentThread], nil);    }];}/** NSBlockOperation */- (void)opDemo2{    for (int i = 0; i < 10; i++) {        // 指定一个块操作        NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{            NSLog(@"下载开始 %@ - %@", [NSThread currentThread], @(i));        }];                // 将块操作添加到队列        [self.queue addOperation:op1];    }}#pragma mark Invocation的调度方法- (void)download:(id)obj{    NSLog(@"下载开始 %@ - %@", [NSThread currentThread], obj);}/** NSInvocationOperation */- (void)opDemo1{    for (int i = 0; i < 10; i++) {        NSInvocationOperation *op1 = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(download:) object:@(i)];                // 如果直接启动，会在主线程执行        //    [op1 start];        // 添加到队列，就会新建线程，异步执行        [self.queue addOperation:op1];    }}@end//头文件@interface NSOperation : NSObject {- (id)init; // designated initializer//开始任务- (void)start;- (void)main;//任务是否取消- (BOOL)isCancelled;- (void)cancel;//是否正在执行- (BOOL)isExecuting;//是否完成执行- (BOOL)isFinished;- (BOOL)isConcurrent;- (BOOL)isReady;//队列之间的依赖操作使用的方法- (void)addDependency:(NSOperation *)op;- (void)removeDependency:(NSOperation *)op;//队列组依赖- (NSArray *)dependencies;//队列优先级- (NSOperationQueuePriority)queuePriority;- (void)setQueuePriority:(NSOperationQueuePriority)p;#if NS_BLOCKS_AVAILABLE- (void (^)(void))completionBlock NS_AVAILABLE(10_6, 4_0);- (void)setCompletionBlock:(void (^)(void))block NS_AVAILABLE(10_6, 4_0);#endif//等待直到完成- (void)waitUntilFinished NS_AVAILABLE(10_6, 4_0);- (double)threadPriority NS_AVAILABLE(10_6, 4_0);- (void)setThreadPriority:(double)p NS_AVAILABLE(10_6, 4_0);@endNS_CLASS_AVAILABLE(10_6, 4_0)@interface NSBlockOperation : NSOperation {@private    id _private2;    void *_reserved2;}#if NS_BLOCKS_AVAILABLE+ (id)blockOperationWithBlock:(void (^)(void))block;- (void)addExecutionBlock:(void (^)(void))block;- (NSArray *)executionBlocks;#endif@end- (id)initWithTarget:(id)target selector:(SEL)sel object:(id)arg;- (id)initWithInvocation:(NSInvocation *)inv;// designated initializer- (NSInvocation *)invocation;- (id)result;@endFOUNDATION_EXPORT NSString * const NSInvocationOperationVoidResultException NS_AVAILABLE(10_5, 2_0);FOUNDATION_EXPORT NSString * const NSInvocationOperationCancelledException NS_AVAILABLE(10_5, 2_0);N- (void)addOperation:(NSOperation *)op;- (void)addOperations:(NSArray *)ops waitUntilFinished:(BOOL)wait NS_AVAILABLE(10_6, 4_0);#if NS_BLOCKS_AVAILABLE- (void)addOperationWithBlock:(void (^)(void))block NS_AVAILABLE(10_6, 4_0);#endif//队列组- (NSArray *)operations;- (NSUInteger)operationCount NS_AVAILABLE(10_6, 4_0);//最大并发数- (NSInteger)maxConcurrentOperationCount;- (void)setMaxConcurrentOperationCount:(NSInteger)cnt;enum {    NSOperationQueueDefaultMaxConcurrentOperationCount = -1};//设置暂停- (void)setSuspended:(BOOL)b;- (BOOL)isSuspended;//设置名字- (void)setName:(NSString *)n NS_AVAILABLE(10_6, 4_0);- (NSString *)name NS_AVAILABLE(10_6, 4_0);//取消所有人去- (void)cancelAllOperations;//等待所有任务完成- (void)waitUntilAllOperationsAreFinished;//当前队列+ (id)currentQueue NS_AVAILABLE(10_6, 4_0);//主队列+ (id)mainQueue NS_AVAILABLE(10_6, 4_0);@end