NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(run) object:nil];
[thread start];

[NSThread detachNewThreadSelector:@selector(run) toTarget:self withObject:nil];
[self performSelectorInBackground:@selector(run) withObject:nil];

主线程相关用法
+ (NSThread *)mainThread; // 获得主线程
- (BOOL)isMainThread; // 是否为主线程
+ (BOOL)isMainThread; // 是否为主线程

NSThread *current = [NSThread currentThread];//获得当前线程

+ (double)threadPriority;
+ (BOOL)setThreadPriority:(double)p;
- (double)threadPriority;
- (BOOL)setThreadPriority:(double)p;
/*调度优先级的取值范围是0.0 ~ 1.0，默认0.5，值越大，优先级越高*/

- (void)setName:(NSString *)n;
- (NSString *)name;

NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(run) object:nil];
[thread start];

+ (void)sleepUntilDate:(NSDate *)date;
+ (void)sleepForTimeInterval:(NSTimeInterval)ti;
// 进入阻塞状态

+ (void)exit;
// 进入死亡状态

@synchronized(锁对象) { // 需要锁定的代码  }

@property (assign, atomic) int age;
- (void)setAge:(int)age
{
    @synchronized(self) {
        _age = age;
    }
}