多线程复习

//
//  ViewController.m
//  NSBlockOperation
//
//  Created by yons on 10/23/18.
//  Copyright © 2018 yons. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *iv;

@end

NSOperationQueue* queue;

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    queue = [[NSOperationQueue alloc]init];
    queue.maxConcurrentOperationCount = 10;
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    
    NSString* url = @"http://img.zcool.cn/community/0117e2571b8b246ac72538120dd8a4.jpg@1280w_1l_2o_100sh.jpg";
    // 以传入的代码块作为执行体，创建NSOperation
    NSBlockOperation* operation = [NSBlockOperation
                                   blockOperationWithBlock:^{
                                       // 从网络获取数据
                                       NSData *data = [[NSData alloc]
                                                       initWithContentsOfURL:[NSURL URLWithString:url]];
                                       // 将网络数据初始化为UIImage对象
                                       UIImage *image = [[UIImage alloc]initWithData:data];
                                       if(image != nil)
                                       {
                                           
//                                         //  主线程方法 1
                                           // 在主线程中执行updateUI:
//                                           [self performSelectorOnMainThread:@selector(updateUI:)
//                                                                  withObject:image waitUntilDone:YES];
                                           
                                           
                                            //  主线程方法 2
//                                           [[NSOperationQueue mainQueue] addOperationWithBlock:^{
//
//                                              self.iv.image = image;
//                                               NSLog(@"UI---%@",[NSThread currentThread]);
//                                           }];
                                           
                                           
                                           //  主线程方法 3
                                           dispatch_async(dispatch_get_main_queue(), ^{
                                              self.iv.image = image;
                                           });
                                           
                                           
                                           
                                           
                                       }
                                       else
                                       {
                                           NSLog(@"---下载图片出现错误---");
                                       }
                                   }];

    [queue addOperation:operation];
}

-(void)updateUI:(UIImage*) image
{
   self.iv.image = image;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end