一、NSThread优缺点
优点：NSThread是最轻量级的
缺点：需要自己管理线程的生命周期，线程同步。线程同步对数据的加锁会有一定的系统开销
二、NSThread的使用
- 创建线程：
+ (void)detachNewThreadSelector:(SEL)selector toTarget:(id)target withObject:(nullableid)argument;
- (instancetype)initWithTarget:(id)target selector:(SEL)selector object:(nullableid)argument; //argument:传输给target的唯一参数，也可以是nil
- 直接创建线程，并开始执行线程
[NSThread detachNewThreadSelector:@selector(doSomething:) toTarget:self withObject:nil];
- 先创建线程对象，然后再运行线程操作，在运行线程操作前可以设置线程的优先级等线程信息
NSThread* myThread = [[NSThread alloc] initWithTarget:self
selector:@selector(doSomething:)
object:nil];
[myThread start];
- 不显式创建线程的方法，Swift中去掉了这个方法，苹果认为 performSelector: 不安全，，，，，
NSObject *obj;
[obj performSelectorInBackground:@selector(doSomething) withObject:nil];
例子：
- (void)viewDidLoad {
[super viewDidLoad];
// [NSThread detachNewThreadSelector:@selector(downloadImage:) toTarget:self withObject:kURL];
NSURL *url = [NSURL URLWithString:@"http://h.hiphotos.baidu.com/image/pic/item/5366d0160924ab1828b7c95336fae6cd7b890b34.jpg"];
NSThread *thread = [[NSThread alloc]initWithTarget:self selector:@selector(downloadImage:) object:url];
[thread start];
}
NSURL *url = [NSURL URLWithString:@"http://h.hiphotos.baidu.com/image/pic/item/5366d0160924ab1828b7c95336fae6cd7b890b34.jpg"];
NSThread *thread = [[NSThread alloc]initWithTarget:self selector:@selector(downloadImage:) object:url];
[thread start];
}
- (void)downloadImage:(NSString *)url {
NSData *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:url]];
UIImage *image = [[UIImage alloc]initWithData:data];
if(image == nil){
}else{
[self performSelectorOnMainThread:@selector(updateUI:) withObject:image waitUntilDone:YES];
}
}
NSData *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:url]];
UIImage *image = [[UIImage alloc]initWithData:data];
if(image == nil){
}else{
[self performSelectorOnMainThread:@selector(updateUI:) withObject:image waitUntilDone:YES];
}
}
- (void)updateUI:(UIImage *)image {
self.iconView.image = image;
}
- 更新其他线程
- (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(nullable id)arg waitUntilDone:(BOOL)wait modes:(nullable NSArray<NSString *> *)array
- (void)performSelector:(SEL)aSelector onThread:(NSThread *)thr withObject:(nullable id)arg waitUntilDone:(BOOL)wait
- 常用属性
//取消线程
- (void)cancel;
//启动线程
- (void)start;
//判断某个线程的状态的属性
@property (readonly, getter=isExecuting) BOOL executing;
@property (readonly, getter=isFinished) BOOL finished;
@property (readonly, getter=isCancelled) BOOL cancelled;
//设置和获取线程名字
-(void)setName:(NSString *)n;
-(NSString *)name;
//获取当前线程信息
+ (NSThread *)currentThread;
//获取主线程信息
+ (NSThread *)mainThread;
//使当前线程暂停一段时间，或者暂停到某个时刻
+ (void)sleepForTimeInterval:(NSTimeInterval)time;
- (void)cancel;
//启动线程
- (void)start;
//判断某个线程的状态的属性
@property (readonly, getter=isExecuting) BOOL executing;
@property (readonly, getter=isFinished) BOOL finished;
@property (readonly, getter=isCancelled) BOOL cancelled;
//设置和获取线程名字
-(void)setName:(NSString *)n;
-(NSString *)name;
//获取当前线程信息
+ (NSThread *)currentThread;
//获取主线程信息
+ (NSThread *)mainThread;
//使当前线程暂停一段时间，或者暂停到某个时刻
+ (void)sleepForTimeInterval:(NSTimeInterval)time;
+ (void)sleepUntilDate:(NSDate *)date;