NSOperation简介
1.实现多线程编程步骤:
配合使用NSOperation和NSOperationQueue实现多线程编程,我们不用考虑线程的生命周期、同步、加锁等问题,如下:
- 先将需要执行的操作封装到一个NSOperation对象中
- 然后将NSOperation对象添加到NSOperationQueue中
- 系统会自动将NSOperation中封装的操作放到一条新线程中执行
2.NSOperation的子类:
NSOperation是个抽象类,并不具备封装操作的能力,必须使⽤它的子类,使用NSOperation⼦类的方式有3种:
- NSInvocationOperation
- NSBlockOperation
- 自定义子类继承NSOperation,实现内部相应的⽅法
封装操作到NSOperation对象中(步骤一)
1.NSInvocationOperation
- (void)invocationOperation {
//封装操作(任务)
//注意:默认情况下,调用了start方法后并不会开一条新线程去执行操作,而是在当前线程同步执行操作。只有将operation放到一个NSOperationQueue中,才会异步执行操作
NSInvocationOperation *op1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(startExecute:) object:@"funky"];
[op1 start];
}
- (void)startExecute:(NSString *)param {
NSLog(@"-------线程:%@ ------ 参数:%@",[NSThread currentThread],param);
//执行操作...
}
NSInvocationOperation封装操作
2.NSBlockOperation
- (void)blockOperation {
//注意:如果一个操作中的任务数量大于1,那么会开子线程并发执行任务,但不一定是子线程,有可能是主线程
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"----- %@",[NSThread currentThread]);
//执行操作...
}];
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"----- %@",[NSThread currentThread]);
//执行操作...
}];
[op1 addExecutionBlock:^{
//op1追加任务1...
}];
[op1 addExecutionBlock:^{
//op1追加任务2...
}];
[op start];
[op1 start];
}
NSBlockOperation封装及追加任务
添加到NSOperationQueue中(步骤二)
1.NSInvocationOperation对象添加到NSOperationQueue中
- (void)invocationOperationWithQueue {
//1.封装操作(任务)
NSInvocationOperation *op1 = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(startExecute:) object:@"funky"];
//2.创建队列(主队列,非主队列)
//主队列 : [NSOperationQueue mainQueue]; (同GCD的主队列,串行队列)
//非主队列 : [[NSOperationQueue alloc]init]; (同时具备并发和串行的功能,默认是并发队列)
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
//3.把操作添加到队列中 (内部已经调用了 [op1 start])
[queue addOperation:op1];
}
- (void)startExecute:(NSString *)param {
NSLog(@"-------线程:%@ ------ 参数:%@",[NSThread currentThread],param);
//执行操作...
}
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2.NSBlockOperation对象添加到NSOperationQueue中及简便方式
- (void)blockOperationWithQueue {
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"----- %@",[NSThread currentThread]);
//执行操作...
}];
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"----- %@",[NSThread currentThread]);
//执行操作...
}];
//创建队列
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
//添加到队列中
[queue addOperation:op];
[queue addOperation:op1];
}
//或简便方法
-(void)simpleWay{
//创建队列
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
[queue addOperationWithBlock:^{
NSLog(@"开子线程执行任务----%@",[NSThread currentThread]);
}];
}
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3.自定义子类继承NSOperation
#import "CustomOperation.h"
@implementation CustomOperation
//重写main方法,在main方法中 执行操作
//可以提高代码复用性
-(void)main {
NSLog(@"----- %@",[NSThread mainThread]);
}
@end
继承于NSOperation的自定义类.m
- (void)customOperationWithQueue {
CustomOperation *op = [[CustomOperation alloc]init];
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
[queue addOperation:op];
}
使用CustomOperation
NSOperation的其他用法
1.NSOperation系统的子类的取消,暂定操作
//开始执行任务
- (IBAction)startBtnClick:(UIButton *)sender {
self.queue = [[NSOperationQueue alloc]init];
//maxConcurrentOperationCount 最大并发数(同一时间最多有多少条任务可以执行)
// >1并发队列 =1串行队列 =0不执行任务 =-1默认,代表最大值,最大并发数不受限制
self.queue.maxConcurrentOperationCount = 1;
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
for (int i =0; i < 1000; i++) {
NSLog(@"download1-----%@",[NSThread currentThread]);
}
}];
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
for (int i =0; i < 1000; i++) {
NSLog(@"download2-----%@",[NSThread currentThread]);
}
}];
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
for (int i =0; i < 1000; i++) {
NSLog(@"download3-----%@",[NSThread currentThread]);
}
}];
[self.queue addOperation:op1];
[self.queue addOperation:op2];
[self.queue addOperation:op3];
}
//暂停执行任务
- (IBAction)stopBtnClick:(UIButton *)sender {
//可恢复,不能暂停当前正处于执行状态的任务
[self.queue setSuspended:YES];
}
//继续执行任务
- (IBAction)goOnBtnClick:(UIButton *)sender {
[self.queue setSuspended:NO];
}
//取消执行任务
- (IBAction)cancelBtnClick:(UIButton *)sender {
//不可恢复
//该方法内部调用了所有operation的cancel方法
[self.queue cancelAllOperations];
}
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2.自定义NSOperation的取消操作
//开始执行任务
- (IBAction)startBtnClick:(UIButton *)sender {
self.queue = [[NSOperationQueue alloc]init];
self.queue.maxConcurrentOperationCount = 1;
HSOperation *op = [[HSOperation alloc]init];
[self.queue addOperation:op];
}
//取消执行任务
- (IBAction)cancelBtnClick:(UIButton *)sender {
//不可恢复
//该方法内部调用了所有operation的cancel方法
[self.queue cancelAllOperations];
}
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#import "HSOperation.h"
@implementation HSOperation
-(void)main {
//3个耗时操作,但相当于一个任务
for (int i =0; i < 1000; i++) {
//if (self.isCancelled) return; 写在这会耗费性能,不建议在这进行操作
NSLog(@"download1-----%@",[NSThread currentThread]);
}
//检测是否取消了操作
if (self.isCancelled) return;
for (int i =0; i < 1000; i++) {
NSLog(@"download2-----%@",[NSThread currentThread]);
}
if (self.isCancelled) return;
for (int i =0; i < 1000; i++) {
NSLog(@"download3-----%@",[NSThread currentThread]);
}
}
@end
HSOperation.m
3.操作依赖及操作监听
-(void)addDependency{
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
NSBlockOperation *op1 = [NSBlockOperation blockOperationWithBlock:^{
//耗时操作1...
NSLog(@"download1-----%@",[NSThread currentThread]);
}];
NSBlockOperation *op2 = [NSBlockOperation blockOperationWithBlock:^{
//耗时操作2...
NSLog(@"download2-----%@",[NSThread currentThread]);
}];
NSBlockOperation *op3 = [NSBlockOperation blockOperationWithBlock:^{
//耗时操作3...
NSLog(@"download3-----%@",[NSThread currentThread]);
}];
NSBlockOperation *op4 = [NSBlockOperation blockOperationWithBlock:^{
//耗时操作4...
NSLog(@"download4-----%@",[NSThread currentThread]);
}];
//操作监听
op3.completionBlock = ^{
NSLog(@"download3下载完成了-----%@",[NSThread currentThread]);
};
//操作依赖
[op1 addDependency:op2]; //op1 等待 op2执行后 在执行
[op2 addDependency:op4];
[op4 addDependency:op3];
// [op3 addDependency:op1]; 不能循环依赖
[queue addOperation:op1];
[queue addOperation:op2];
[queue addOperation:op3];
[queue addOperation:op4];
}
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NSOperation线程间的通信
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
NSOperationQueue *queue = [[NSOperationQueue alloc]init];
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
NSURL *url = [NSURL URLWithString:@"https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1490335106967&di=7daac700f5a1425d58131134228ea9bc&imgtype=0&src=http%3A%2F%2Fsh.sinaimg.cn%2Fcr%2F2013%2F1204%2F533155851.jpg"];
NSData *imgData = [NSData dataWithContentsOfURL:url];
UIImage *image = [UIImage imageWithData:imgData];
NSLog(@"download---%@",[NSThread currentThread]);
//回到主线程刷新UI
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
self.imageView.image = image;
NSLog(@"UI---%@",[NSThread currentThread]);
}];
}];
[queue addOperation:op];
}
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