iOS 底层 - runloop之用C语言实现线程保活

本文源自本人的学习记录整理与理解，其中参考阅读了部分优秀的博客和书籍，尽量以通俗简单的语句转述。引用到的地方如有遗漏或未能一一列举原文出处还望见谅与指出，另文章内容如有不妥之处还望指教，万分感谢 ！

XYHPermenantThread

XYHPermenantThread .h

#import <Foundation/Foundation.h>

typedef void (^XYHPermenantThreadTask)(void);

@interface XYHPermenantThread : NSObject

/**
 在当前子线程执行一个任务
 */
- (void)executeTask:(XYHPermenantThreadTask)task;

/**
 结束线程
 */
- (void)stop;

@end

XYHPermenantThread.m

#import "XYHPermenantThread.h"

/** XYHThread **/
@interface XYHThread : NSThread
@end
@implementation XYHThread
- (void)dealloc
{
    NSLog(@"%s", __func__);
}
@end

/** XYHPermenantThread **/
@interface XYHPermenantThread()
@property (strong, nonatomic) XYHThread *innerThread;
@end

@implementation XYHPermenantThread
#pragma mark - public methods
- (instancetype)init
{
    if (self = [super init]) {

        self.innerThread = [[XYHThread alloc] initWithBlock:^{
            NSLog(@"begin----");
            
            // 创建上下文（要初始化一下结构体）
            CFRunLoopSourceContext context = {0};
            
            // 创建source
            CFRunLoopSourceRef source = CFRunLoopSourceCreate(kCFAllocatorDefault, 0, &context);
            
            // 往Runloop中添加source
            CFRunLoopAddSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode);
            
            // 销毁source
            CFRelease(source);
           
           /** 
           启动loop
           第3个参数：returnAfterSourceHandled，
           设置为true，代表执行完source后就会退出当前loop
           设置为false，代表执行完source后就不在退出当前loop
           */
           CFRunLoopRunInMode(kCFRunLoopDefaultMode, 1.0e10, false);

            NSLog(@"end----");
        }];
        //开始跑起来
        [self.innerThread start];
    }
    return self;
}

- (void)executeTask:(XYHPermenantThreadTask)task
{
    if (!self.innerThread || !task) return;

    //执行任务时wait需要设置为NO,不需要别人等；这种操作在RunLoop中是属于Sources0
    [self performSelector:@selector(__executeTask:) onThread:self.innerThread withObject:task waitUntilDone:NO];

}

- (void)stop
{
    if (!self.innerThread) return;
    
  //暂停时wait需要设置为YES；因为需要别人等，防止还没停止当前实例对象就先释放掉了。这种操作在RunLoop中是属于Sources0
    [self performSelector:@selector(__stop) onThread:self.innerThread withObject:nil waitUntilDone:YES];
}

#pragma mark - private methods
- (void)__stop
{
    CFRunLoopStop(CFRunLoopGetCurrent());
    self.innerThread = nil;
}

- (void)__executeTask:(XYHPermenantThreadTask)task
{
    task();
}

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

使用：-------->>>>>>>>>>>>>>>--------

#import "ViewController.h"
#import "XYHPermenantThread.h"

@interface ViewController ()
@property (strong, nonatomic) XYHPermenantThread *thread;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.thread = [[XYHPermenantThread alloc] init];
}

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

- (IBAction)stop {
    [self.thread stop];
}

- (void)dealloc
{
    NSLog(@"%s", __func__);
}