IOS7笔记-10多线程滚动视图

Posted 2020-07-24 Faint@LastStep

１、滚动视图使用方方法：

 1 @interface ImageViewController ()<UIScrollViewDelegate>//声明委托
 2 @property (strong, nonatomic) UIImageView *imageView;
 3 @property (strong, nonatomic) UIImage *image;
 4 @property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
 5 @property (weak, nonatomic) IBOutlet UIActivityIndicatorView *spinner;
 6 @end
 7 
 8 -(void)setScrollView:(UIScrollView *)scrollView
 9 {
10     _scrollView = scrollView;
11     _scrollView.minimumZoomScale = 0.2;　//设置缩放特性
12     _scrollView.maximumZoomScale = 2.0;　//设置缩放特性
13     _scrollView.delegate = self;　//设置委托
14     self.scrollView.contentSize = self.image ? self.image.size : CGSizeZero;　//设置滚动视图可移动特性
15 }
16 
17 //实现缩放委托
18 -(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
19 {
20     return self.imageView;
21 }
22 
23 -(UIImageView *)imageView
24 {
25     if (!_imageView) {
26         _imageView = [[UIImageView alloc] init];
27     }
28     return _imageView;
29 }
30 
31 -(UIImage *)image
32 {
33     return self.imageView.image;
34 }
35 
36 -(void)setImage:(UIImage *)image
37 {
38     self.imageView.image = image;
39     [self.imageView sizeToFit];
40     self.scrollView.contentSize = self.image ? self.image.size : CGSizeZero;　//设置滚动视图可移动特性
41 }
42 
43 -(void)viewDidLoad
44 {
45     [super viewDidLoad];
46     [self.scrollView addSubview:self.imageView];
47 }

２、多线程调用方法

 1 -(void)setImageURL:(NSURL *)imageURL
 2 {
 3     _imageURL = imageURL;
 4     //self.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:self.imageURL]];
 5     [self startDownloadingImage];
 6 }
 7 
 8 -(void)startDownloadingImage
 9 {
10     self.image = nil;
11     if (self.imageURL) {
12         [self.spinner startAnimating];
13         NSURLRequest *request = [NSURLRequest requestWithURL:self.imageURL];//设置请求对象
14         NSURLSessionConfiguration *congiguration = [NSURLSessionConfiguration ephemeralSessionConfiguration];//设置请求任务配置方法
15         NSURLSession *session = [NSURLSession sessionWithConfiguration:congiguration];//定义URL任务
16         NSURLSessionDownloadTask *task = [session downloadTaskWithRequest:request
17             completionHandler:^(NSURL *locationfile, NSURLResponse *response, NSError *error) {
18                 if (!error) {
19                     if ([request.URL isEqual:self.imageURL]) {
20                         UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:locationfile]];
21                         //self.image = image;
22                         dispatch_async(dispatch_get_main_queue(), ^{
23                             self.image = image;
24                         }); 25                         //[self performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:NO];
26                     }
27                 }
28             }];//定义一个线程任务 在子线程中调用网络下载，并把在下载成功的图片在主线程中调用显示
29         [task resume];//恢复任务线程执行，创建任务时默认是挂起状态，需要恢复才能真正执行
30     }
31 }