在看線程鎖時(shí)，無(wú)意間看到block的遞歸調(diào)用，之前一直沒(méi)有想怎么進(jìn)行block遞歸調(diào)用，這里記錄一下。

    static NSRecursiveLock *lock;
    
    if (lock == nil) {
        
        lock = [[NSRecursiveLock alloc] init];
        
    }
    
    static void (^__block DoLog)(int) = ^(int value){
        
        [lock lock];
        
        if (value > 0) {
            
            DoLog(value-1);
            
        }
        
        NSLog(@"value is %d", value);
        
        [lock unlock];
        
    };
    
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        
        NSLog(@"test begin");
        
        DoLog(5);
        
        NSLog(@"test end");
        
    });