ios - 无法在屏幕上显示，Xcode6.1.1

Question

所以我整天都在寻找并修复了一些，但仍然无法显示。因此，交易如下:

我已经开始编写 Xcode 3 天了，我正在网上关注斯坦福大学的讲座，所以代码看起来就像讲座代码。尽管几乎所有内容都与讲座代码相同，但我的代码无法显示从互联网上获取的单词。目的是建立一本字典，如果我能够在我的模拟设备 iPhone 6 上看到单词，我将继续写作。

我无法理解的是，我向窗口发送一条消息并说它采用导航 Controller ，我在其中推送了 WordListViewController(您可以在下面的代码中的 AppDelegate.m 段中看到)。

您可以在下面找到我的代码:

WordListTableViewController.h

//
//  WordListTableViewController.h
//  Vocabulous
//
//  Created by user30357 on 6/19/15.
//  Copyright (c) 2015 user30357. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface WordListTableViewController : UIViewController <UITableViewDelegate, UITableViewDataSource>{
    NSMutableDictionary *words;
    NSArray *sections;
}

@end

WordListTableViewController.m

//
//  WordListTableViewController.m
//  Vocabulous
//
//  Created by user30357 on 6/19/15.
//  Copyright (c) 2015 user30357. All rights reserved.
//

#import "WordListTableViewController.h"

@interface WordListTableViewController ()
@property (nonatomic, retain) NSMutableDictionary *words;
@property (nonatomic, retain) NSArray *sections;
@end

@implementation WordListTableViewController

@synthesize words, sections;

- (NSMutableDictionary *) words{
    if(!words){
        NSURL *wordsURL = [NSURL URLWithString:@"http://cs193p.stanford.edu/vocabwords.txt"];
        words = [[NSMutableDictionary dictionaryWithContentsOfURL:wordsURL] retain];
    }
    return words;
}

- (NSArray *) sections{
    if(!sections){
        sections = [[[self.words allKeys] sortedArrayUsingSelector:@selector(compare:)] retain];
    }
    return sections;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    // Uncomment the following line to preserve selection between presentations.
    // self.clearsSelectionOnViewWillAppear = NO;

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;
}

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

- (void)dealloc{
    [words release];
    [sections release];
    [super dealloc];
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return self.sections.count;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    NSArray *wordsInSection = [self.words objectForKey:[self.sections objectAtIndex:section]];
    return wordsInSection.count;
}

- (NSString *) wordAtIndexPath:(NSIndexPath *) indexPath{
    NSArray *wordsInSection = [self.words objectForKey:[self.sections objectAtIndex:indexPath.section]];
    return [wordsInSection objectAtIndex:indexPath.row];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    NSString *identifier = @"WordListTableViewCell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];

    if(cell == nil)
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];

    // Configure the cell...
    cell.textLabel.text = [self wordAtIndexPath:indexPath];
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    return cell;
}


/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
    // Return NO if you do not want the specified item to be editable.
    return YES;
}
*/

/*
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    } else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}
*/

/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
}
*/

/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath {
    // Return NO if you do not want the item to be re-orderable.
    return YES;
}
*/

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

AppDelegate.h

//
//  AppDelegate.h
//  Vocabulous
//
//  Created by user30357 on 6/19/15.
//  Copyright (c) 2015 user30357. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;


@end

AppDelegate.m

//
//  AppDelegate.m
//  Vocabulous
//
//  Created by user30357 on 6/19/15.
//  Copyright (c) 2015 user30357. All rights reserved.
//

#import "AppDelegate.h"
#import "WordListTableViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate

@synthesize window;


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.

    WordListTableViewController *wltvc = [[WordListTableViewController alloc] init];
    UINavigationController *nav = [[UINavigationController alloc] init];
    [nav pushViewController:wltvc animated:NO];
    [wltvc release];
    [window addSubview:nav.view];
    [window makeKeyAndVisible];
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
    // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}

- (void)applicationDidBecomeActive:(UIApplication *)application {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

- (void)applicationWillTerminate:(UIApplication *)application {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}

@end

这 4 个都是我的类(class)。此外，我的 Storyboard有 WordListTableViewController 类，因为我删除了 ViewController。

希望你能帮助我解决这个问题，因为我真的快要疯了!

从现在开始感谢!

Answer 1

您没有初始化窗口。这是我启动项目的方法。

在AppDelegate.h

@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) UINavigationController *navigator;

和@synthesize它们。

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    self.window=[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    LoginViewController *controller=[[LoginViewController alloc] init];
    navigator = [[UINavigationController alloc] initWithRootViewController:controller];
    [self.window setRootViewController:navigator];
    [self.window makeKeyAndVisible];


    // Override point for customization after application launch.
    return YES;
}