寫在前面

本文主要講一下線程保活是什么赖舟、線程北鲎ィ活的意義裕偿、如何實(shí)現(xiàn)線程蓖吹ィ活旭绒。

線程保活

線程生命周期

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什么是線程被藕椋活

線程贝毡＃活：一般情況下，當(dāng)線程執(zhí)行玩一次任務(wù)之后需要進(jìn)行資源回收也就意味著生命周期結(jié)束频伤，線程敝ゴ耍活就是保證線程的生命周期不結(jié)束。

線程卑陡活的應(yīng)用場(chǎng)景

當(dāng)一個(gè)任務(wù)隨時(shí)都有可能去執(zhí)行它怎炊，那么這個(gè)任務(wù)應(yīng)該放在子線程去執(zhí)行，并且讓子線程一直存活债查，避免頻繁創(chuàng)建線程而造成的性能損耗瓜挽。
大家如果看過AFNetworking的源碼就會(huì)看到框架里面是有用到線程本贸龋活的。

如何實(shí)現(xiàn)線程卑溃活

// WWPermenantThread 類
@interface WWPermenantThread : NSObject

/**
 關(guān)閉線程
 */
- (void)stop;

/// 在钡叻牛活的線程里面執(zhí)行的任務(wù)
/// @param target 目標(biāo)對(duì)象
/// @param action selector
/// @param object object
- (void)excuteTaskWithTarget:(id)target action:(SEL)action object:(id)object;

/// 在保活的線程里執(zhí)行任務(wù)
/// @param task 執(zhí)行的任務(wù)
- (void)excuteTask:(void(^)(void))task;

@end

@interface WWPermenantThread ()

@property (nonatomic, strong) NSThread *innerThread;
@property (nonatomic, assign) BOOL isStopped;

@end

@implementation WWPermenantThread

- (void)dealloc {
    NSLog(@"%s",__func__);
    [self stop];
}

- (instancetype)init {
  if (self = [super init]) {
    self.isStopped = NO;

    __weak typeof(self) weakSelf = self;
    self.innerThread = [[NSThread alloc] initWithBlock:^{
      // 添加Port到RunLoop
      [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc] init] forMode:NSDefaultRunLoopMode];
      while (weakSelf && !weakSelf.isStopped) {
        // 開啟RunLoop
          [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
      }
    }];
    [self.innerThread start];
  }
  return self;
}

- (void)run {
  if (!self.innerThread) {
      return;
  }
  [self.innerThread start];
}

- (void)stop {
  if (!self.innerThread) {
      return;
  }
  [self performSelector:@selector(__stop) onThread:self.innerThread withObject:nil waitUntilDone:YES];
}

- (void)__stop {
  self.isStopped = YES;
  // 退出當(dāng)前RunLoop
  CFRunLoopStop(CFRunLoopGetCurrent());
  self.innerThread = nil;
}

- (void)excuteTaskWithTarget:(id)target action:(SEL)action object:(id)object {
  if (!self.innerThread) {
      return;
  }
  [self performSelector:action onThread:self.innerThread withObject:object waitUntilDone:NO ];
}

- (void)excuteTask:(void (^)(void))task {
  if (!self.innerThread || !task) {
      return;
  }
  [self performSelector:@selector(__excuteTask:) onThread:self.innerThread withObject:task waitUntilDone:NO ];
}

- (void)__excuteTask:(void(^)(void))task {
  task();
}

@end

如何使用線程笨愿遥活

- (void)viewDidLoad {
  [super viewDidLoad];
  // 創(chuàng)建一個(gè)線程對(duì)象
  self.thread = [[WWPermenantThread alloc] init];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
  [self.thread excuteTask:^{
      NSLog(@"執(zhí)行任務(wù) - %@", [NSThread currentThread]);
  }];
}

執(zhí)行結(jié)果：

2023-02-15 10:18:56.211402+0800 線程迸鲂祝活Demo1[10526:21512893] 執(zhí)行任務(wù) - <NSThread: 0x600002e99680>{number = 9, name = (null)}
2023-02-15 10:18:56.830085+0800 線程保活Demo1[10526:21512893] 執(zhí)行任務(wù) - <NSThread: 0x600002e99680>{number = 9, name = (null)}
2023-02-15 10:18:57.279150+0800 線程甭雇眨活Demo1[10526:21512893] 執(zhí)行任務(wù) - <NSThread: 0x600002e99680>{number = 9, name = (null)}
2023-02-15 10:18:58.212741+0800 線程庇停活Demo1[10526:21512893] 執(zhí)行任務(wù) - <NSThread: 0x600002e99680>{number = 9, name = (null)}
2023-02-15 10:19:32.672529+0800 線程保活Demo1[10526:21512038] -[OneViewController dealloc]
2023-02-15 10:19:32.672800+0800 線程毙笪活Demo1[10526:21512038] -[WWPermenantThread dealloc]

寫在最后

關(guān)于如何實(shí)現(xiàn)線程崩常活的筆記就記錄到這里了凄鼻，如有錯(cuò)誤請(qǐng)多多指教腊瑟，最后歡迎去我的個(gè)人技術(shù)博客逛逛。