CS193p Lecture 10 - Multithreating, UIScrollView

Multithreating（多线程）

网络请求例子：

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://..."]];
NSURLSessionConfiguration *configuration = nil;
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration];
NSURLSessionDownloadTask *task;
task = [session downloadTaskWithRequest:request
                      completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
                          dispatch_async(dispatch_get_main_queue(), ^{/* do UI thing */});
                          // or [self performSelectorOnMainThread:@selector(doUIthings) withObject:nil waitUntilDone:NO];
                      }];
[task resume];

在完成网络请求后，做一些UI操作，UI操作是在主线程完成

UIScrollView（滚动视图）

注意：需要设置scrollView的contentSize

scrollView.contentSize = CGSizeMake(3000, 2000);

设置缩放比例

scrollView.minimumZoomScale = 2.0;

scrollView.minimumZoomScale = 0.2;