大家好，小弟最近想自己试着使用NSURLSession来写写看如何抓到JSON的资料 主要架构就是用一个TableViewControler把抓回来的JSON资料一笔一笔显示出来 上网查了许多资料自己试做後，有成功抓到JSON资料， 但是目前遇到问题是资料回来之前， TableViewController 就已经建立好了， 所以一开APP不会显示资料，我需要等资料回来後， 准备一个执行[TableView reloadData]的方法的按钮， 按下後才能在TableView上显示资料。 我参照网路上以及Apple的一些官方sample， 把抓资料的NSURLSession写在AppDelegate的Class里 可能应为对於能在哪个时机点让APP自动执行reloadData还不是很了解， 想请教各位大大，感恩！ 程式码如下（目前的写法曾经有几次成功在APP执行後自动显示，但成功机率很低..）： static NSString * const taipeiUrl = @"http://data.taipei.gov.tw/opendata/apply/json/RkRDNjk0QzUtNzdGRC00ODFCLUJBNDktNEJCMUVCMDc3ODFE"; @interface AppDelegate () @end @implementation AppDelegate - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { NSURLSession *session = [NSURLSession sharedSession]; NSURLSessionDataTask *dataTask = [session dataTaskWithURL:[NSURL URLWithString:taipeiUrl] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error){ NSLog(@"error = %@", [error description]); if (error != nil) { [[NSOperationQueue mainQueue] addOperationWithBlock: ^{ [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; if ([error code] == NSURLErrorAppTransportSecurityRequiresSecureConnection) { abort(); } else { [self handleError:error]; } }]; } else{ NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil]; self.newsArray = [json valueForKey:@"name"]; NSLog(@"%@", self.newsArray); __weak AppDelegate *weakSelf = self; dispatch_async(dispatch_get_main_queue(), ^(void){ NewsTableViewController *rootViewController = (NewsTableViewController *)[(UINavigationController *)weakSelf.window.rootViewController topViewController]; [rootViewController.tableView reloadData]; }); // show in the status bar that network activity is starting [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; } }]; [dataTask resume]; //UI self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; //create the navigation controller and add the controllers view to the window self.navigationController = [[UINavigationController alloc] init]; [self.window addSubview:[self.navigationController view]]; NewsTableViewController *newsViewController = [[NewsTableViewController alloc] initWithNibName:@"NewsTableViewController" bundle:nil]; //push the first viewcontroller into the navigation view controller stack [self.navigationController pushViewController:newsViewController animated:YES]; self.window.backgroundColor = [UIColor whiteColor]; self.window.rootViewController = self.navigationController; [self.window makeKeyAndVisible]; // show in the status bar that network activity is starting [UIApplication sharedApplication].networkActivityIndicatorVisible = YES; return YES; } // handleError:error // Reports any error with an alert which was received from connection or loading failures. - (void)handleError:(NSError *)error { NSString *errorMessage = [error localizedDescription]; // alert user that our current record was deleted, and then we leave this view controller // UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Cannot Show Top Paid Apps" message:errorMessage preferredStyle:UIAlertControllerStyleActionSheet]; UIAlertAction *OKAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) { // dissmissal of alert completed }]; [alert addAction:OKAction]; [self.window.rootViewController presentViewController:alert animated:YES completion:nil]; } --

※ 发信站: 批踢踢实业坊(ptt.cc), 来自: 123.193.12.200 ※ 文章网址: https://webptt.com/cn.aspx?n=bbs/MacDev/M.1460805376.A.988.html