[多线程之二]－NSOperation练习

Myth丶恋晨 2022-08-18 13:28 128阅读 0赞

#import <UIKit/UIKit.h>
    
    @interface ViewController : UIViewController
    @property (strong, nonatomic) IBOutlet UIImageView *MainImgView;
    @property (strong, nonatomic) IBOutlet UIImageView *BlockImgView;
    @end

#import "ViewController.h"
    
    @interface ViewController ()
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        NSURL* url = [[NSURL alloc] initWithString:@"http://avatar.csdn.net/3/0/F/1_liyanq528.jpg"];
        //注意1:NSInvocationOperation这个只能传一个参数
        //注意2:NSInvocationOperation直接调用的话，是放在主线程调用，只有用queue里面才是其他线程调用。
        NSInvocationOperation* operat = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downLoadImg:) object:url];
        [operat setCompletionBlock:^{
            NSLog(@"MainImgView图像更新完成");
        }];
        //注意3:NSBlockOperation直接调用只有一个block，是放在主线程调用。有多个block,或者放入queue里面，就可以其他线程调用
        NSBlockOperation* bOperat = [NSBlockOperation blockOperationWithBlock:^{
            NSData* data = [[NSData alloc] initWithContentsOfURL:url];
            if (data) {
                UIImage* img = [[UIImage alloc] initWithData:data];
                NSLog(@"%@",[NSThread currentThread]);
                dispatch_async(dispatch_get_main_queue(), ^{
                    self.BlockImgView.image = img;
                });
                //[self performSelectorOnMainThread:@selector(updateImg:) withObject:img waitUntilDone:NO];
            }
        }];
        [bOperat setCompletionBlock:^{
            NSLog(@"BlockImgView图像更新完成");
        }];
        NSOperationQueue* que = [[NSOperationQueue alloc]init];
        //注意4:并发的线程数量不宜过多，最好5以内，否则会影响ui
        [que setMaxConcurrentOperationCount:3];
        [que addOperation:operat];
        [que addOperation:bOperat];
        [super viewDidLoad];
        // Do any additional setup after loading the view, typically from a nib.
    }
    
    - (void)didReceiveMemoryWarning {
        [super didReceiveMemoryWarning];
        // Dispose of any resources that can be recreated.
    }
    -(void) updateImg:(UIImage*) aimg
    {
        self.MainImgView.image = aimg;
    }
    -(void) downLoadImg:(NSURL*) aurl
    {
        NSData* data = [[NSData alloc] initWithContentsOfURL:aurl];
        if (data) {
            UIImage* img = [[UIImage alloc] initWithData:data];
            dispatch_async(dispatch_get_main_queue(), ^{
                self.MainImgView.image = img;
            });
            //[self performSelectorOnMainThread:@selector(updateImg:) withObject:img waitUntilDone:NO];
        }
    }
    @end

参考：http://www.cnblogs.com/wendingding/p/3809042.html