Objc多线程-NSThread

NSThread

查看NSThread.h中的接口：

类方法不返回NSThread实例，直接在其他线程里面执行任务。

+ (void)detachNewThreadWithBlock:(void(^)(void))block API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0));

+ (void)detachNewThreadSelector:(SEL)selector toTarget:(id)target withObject:(nullableid)argument;

实例方法返回NSThread对象，需要调用start，或者main才能执行，执行完任务，ARC自动回收NSThread对象。

- (instancetype)init NS_AVAILABLE(10_5,2_0) NS_DESIGNATED_INITIALIZER;

- (instancetype)initWithTarget:(id)target selector:(SEL)selector object:(nullableid)argument NS_AVAILABLE(10_5,2_0);

- (instancetype)initWithBlock:(void(^)(void))block API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0));

线程优先级，类方法，实例化NSThread后调用，优先级高的任务先被调度。这个属性即将废弃，改为qualityOfService。

+ (double)threadPriority;

+ (BOOL)setThreadPriority:(double)p;

@property double threadPriority NS_AVAILABLE(10_6,4_0);// To be deprecated; use qualityOfService below

@property NSQualityOfService qualityOfService NS_AVAILABLE(10_10,8_0);// read-only after the thread is started

线程Sleep，类方法，将当前线程sleep。

+ (void)sleepUntilDate:(NSDate *)date;

+ (void)sleepForTimeInterval:(NSTimeInterval)ti;

NSObject (NSThreadPerformAdditions)：以下category方法，在delay后，把事件放到runloop里面，runloop通知相应的线程去执行。这套机制生效的前提是onThread的thread的runloop是开启的。如果子线程runloop未开启，就不会执行selector，如果waitUntilDone为YES，此时就会阻塞当前线程。

@interface NSObject (NSThreadPerformAdditions)

- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullableid)arg waitUntilDone:(BOOL)wait modes:(nullableNSArray *)array;

- (void)performSelectorOnMainThread:(SEL)aSelector withObject:(nullableid)arg waitUntilDone:(BOOL)wait;

// equivalent to the first method with kCFRunLoopCommonModes

- (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(nullableid)arg waitUntilDone:(BOOL)wait modes:(nullableNSArray *)array NS_AVAILABLE(10_5,2_0);

- (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(nullableid)arg waitUntilDone:(BOOL)wait NS_AVAILABLE(10_5,2_0);

// equivalent to the first method with kCFRunLoopCommonModes

- (void)performSelectorInBackground:(SEL)aSelector withObject:(nullableid)arg NS_AVAILABLE(10_5,2_0);

start方法和main方法

You should never invoke this method directly. You should always start your thread by invoking the start method.

开启两个线程NSThread，调用main方法，两个NSThread中的任务顺序由主线程执行。没有起到在子线程中并发。所有不要显式的调用main方法，如[thread main];

一旦NSThread的子类重写了main()方法，[thread start]就只会调用main方法里面的任务，block和selector都不会执行。

- (void)cancel NS_AVAILABLE(10_5,2_0);

- (void)start NS_AVAILABLE(10_5,2_0);

- (void)main NS_AVAILABLE(10_5,2_0);// thread body method

@end