玩转iOS开发 - 多线程开发

前言

NSOperation

简单介绍

NSOperation的子类

NSInvocationOperation

- (id)initWithTarget:(id)target selector:(SEL)sel object:(id)arg;

- (void)start;

1. 运行操作

//创建操作
NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector: @selector(downloadFile:) object:@"fileName"]; //在当前线

//程运行方法(開始运行操作)
[op start];

2. 把操作加入到队列(并開始异步运行)

//创建操作
NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector: @selector(downloadFile:) object:@"fileName"];

//将操作加入到队列,会自己主动异步调用方法
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[queue addOperation:op];

- (void)downloadFile:(id)object
{
NSLog(@"下载:%@----线程:%@",object,[NSThread currentThread]);
}

3. 开启多个线程,不会顺序运行

//队列
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
for (int i = 0; i < 10; i++)
{
//创建操作
NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self selector: @selector(downloadFile:) object:@(i)];

//将操作加入到队列,会自己主动异步调用方法
[queue addOperation:op];
}

- (void)downloadFile:(id)object
{
NSLog(@"下载:%@----线程:%@",object,[NSThread currentThread]);
}

注意：

- (void)addNOperation:(NSOperation *)op;
- (void)addOperationWithBlock:(void(^)(void))block

NSBlockOperation

+ (id)blockOperationWithBlock:(void)^(void)

- (id)addExecutionBlock:(void)(^)(void)block

1. NSBlockOperation

NSOperationQueue *queue = [[NSOperationQueue alloc] init];

for (int i = 0; i < 10; i++)
{
//创建操作
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"down %d %@",i,[NSThread currentThread]);
}];

//把操作加入到队列中
[queue addOperation:op];
}

2. NSOperationQueue加入block的operation

NSOperationQueue *queue = [[NSOperationQueue alloc] init];

for (int i = 0; i < 10; i++)
{
[queue addOperationWithBlock:^{
NSLog(@"down %d %@",i,[NSThread currentThread]);
}];
}

3. 全局操作队列

@property (nonatomic, strong) NSOperationQueue *queue;

//懒载入队列
- (NSOperationQueue *)queue
{
if (_queue == nil)
{
_queue = [[NSOperationQueue alloc] init];
}

return _queue;
}

for (int i = 0; i < 10; i++)
{
[self.queue addOperationWithBlock:^{
NSLog(@"down %d %@",i,[NSThread currentThread]);
}];
}

4. 监听操作完毕

[op1 setCompletionBlock:^{
NSLog(@".....");
}];

并发数

- (NSInteger)maxConcurrentOperationCount;
- (void)setMaxConcurrentOperationCount:(NSInteger)cnt;

注意：

- (void)demo
{
self.queue.maxConcurrentOperationCount = 3;

for (int i=1; i<50; i++)
{
[self.queue addOperationWithBlock:^{
[NSThread sleepForTimeInterval:3.0];
NSLog(@"====%@===%d",[NSThread currentThread],i);
}];

[NSThread sleepForTimeInterval:1.0];
}
}

不加最大并发数：

加入最大并发数：

[ self.queue addOperationWithBlock]

队列的取消，暂停和恢复

取消队列的全部操作

- (void)cancelAllOperations;

- (void)cancel;

暂停和恢复队列

- (void)setSuspended:(BOOL)b; // YES代表暂停队列,NO代表恢复队列

- (BOOL)isSuspended; //当前状态

暂停和恢复的适用场合

演示样例代码-摇奖机

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *lbl0;
@property (weak, nonatomic) IBOutlet UILabel *lbl1;
@property (weak, nonatomic) IBOutlet UILabel *lbl2;

@property (weak, nonatomic) IBOutlet UIButton *btn;
//全局队列
@property (nonatomic, strong) NSOperationQueue *queue;

- (IBAction)start:(UIButton *)sender;
@end

@implementation ViewController

//队列懒载入-> 假设没有初始话queue, 则不会有队列生成，程序不会有响应
- (NSOperationQueue *)queue
{
if (_queue == nil)
{
_queue = [[NSOperationQueue alloc] init];
}
return _queue;
}

- (void)viewDidLoad
{
[super viewDidLoad];
}

- (IBAction)start:(UIButton *)sender
{
//首先要推断队列是否为空->推断队列是否是挂起状态时,并不会推断队列中是否有操作
if(self.queue.operationCount == 0)
{
//假设操作为空，说明运行摇奖，同一时候開始button变暂停
[self.queue addOperationWithBlock:^{
[self random];
}];
[self.btn setTitle:@"停止" forState:UIControlStateNormal];
//当前队列运行。不被挂起
self.queue.suspended = NO;

}
else if(self.queue.isSuspended)
{
//假设当前是挂起状态->開始队列->btn：暂停
self.queue.suspended = NO;
[self.btn setTitle:@"停止" forState:UIControlStateNormal];
}
else
{
//假设当前是运行状态->暂停队列->btn：開始
self.queue.suspended = YES;
[self.btn setTitle:@"開始" forState:UIControlStateNormal];
}

}

- (void)random
{
//假设单签队列没有挂起
while (![NSOperationQueue currentQueue].isSuspended)
{
int num = arc4random_uniform(10);
int num1 = arc4random_uniform(10);
int num2 = arc4random_uniform(10);

[NSThread sleepForTimeInterval:0.05];

[[NSOperationQueue mainQueue] addOperationWithBlock:^{
self.lbl0.text = [NSString stringWithFormat:@"%d",num];
self.lbl1.text = [NSString stringWithFormat:@"%d",num1];
self.lbl2.text = [NSString stringWithFormat:@"%d",num2];
}];
}
}
@end

操作优先级

- (NSOperationQueuePriority)queuePriority;
- (void)setQueuePriority:(NSOperationQueuePriority)p;

操作依赖

[opB addDependency:opA];

1. 模拟软件的部分升级

/*=======依赖关系========*/
/**
*模拟软件的部分升级:下载->解压->通知用户升级
*/
//下载压缩包-> 操作
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"下载 %@",[NSThread currentThread]);
}];

//解压,拷贝到对应文件夹
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"解压 %@",[NSThread currentThread]);
}];

//通知用户
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"通知用户升级完毕 %@",[NSThread currentThread]);
}];

//设置操作的依赖关系
[op2 addDependency:op1];
[op3 addDependency:op2];

//加入操作
/**
*waitUntilFinished YES 等待全部的操作运行完毕 会堵塞窗口的运行
*waitUntilFinished NO 不等待
*/
[self.queue addOperations:@[op1,op2,op3] waitUntilFinished:NO];
NSLog(@"over");

循环依赖

3. 依赖关系能够跨队列运行

[op2 addDependency:op1];
[op3 addDependency:op2];

//子队列
[self.queue addOperations:@[op1,op2] waitUntilFinished:NO];
NSLog(@"over");

[[NSOperationQueue mainQueue] addOperation:op3];

操作的监听

- (void (^)(void))completionBlock;
- (void)setCompletionBlock:(void (^)(void))block;

- (void)demo
{
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
for (int i=1; i<3; i++)
{
[NSThread sleepForTimeInterval:1.0];
NSLog(@"%@==download image = %d",[NSThread currentThread], i);
}
}];

[self.queue addOperation:op];

op.completionBlock =^{
NSLog(@"finishing download image, do ot
her things");
};

NSLog(@"%@====I'm later than downloading image",[NSThread currentThread]);
}

GCD和NSOperation的比較

GCD

NSOperation

困了,待续,最近更新……

GCD

NSThread

Pthread