ios - 在 iOS 上加载 NSBundle 文件

Question

我想创建一个具有非常灵活的图形用户界面(可换肤)的项目。为了使这成为可能，我想从外部资源加载一个 NSBundle，例如一个网站。该包应包含与主项目中的某些属性和方法相对应的 nib(IBOutlets 和 IBActions)

Apple 似乎限制了以这种方式使用 NSBundle 的可能性。有什么办法可以使这项工作吗？如果以传统方式无法实现，那么推荐的替代方法是什么？

Answer 1

正如所 promise 的，这里有一个简短的解释，说明我是如何让它工作的。

在我的 AppDelegate 中，我检查服务器上是否有新的 bundle (打包在 zip 文件中)。如果存在，我会下载 bundle 。该 bundle 包含我的可换肤图形界面和其他相关数据(例如图形文件)所需的 Nib 。代码看起来有点像这样:

TestAppDelegate.m

- (void)downloadBundle 
{      
   NSURL *url = [NSURL URLWithString:@"http://127.0.0.1/~wsc/template.bundle.zip"];
   NSURLRequest *request = [NSURLRequest requestWithURL:url];
   NSURLResponse *response = nil;
   NSError *error = nil;
   NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
   NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
   NSLog(@"%d", [httpResponse statusCode]);

   if ([httpResponse statusCode] == 404) // bundle will be deleted and the default interface will be used ...
   {
      NSString *path = [documentsDirectory stringByAppendingPathComponent:@"template.bundle"];
      [[NSFileManager defaultManager] removeItemAtPath:path error:nil];
      return;
   }
   else if (error) 
   {
      NSLog(@"%@", error);
   }

   BOOL didWriteData = [data writeToFile:zipFile atomically:YES];
   if (didWriteData) 
   {
      BOOL success = [SSZipArchive unzipFileAtPath:zipFile toDestination:documentsDirectory];
      if (!success) 
      {
         NSLog(@"failed to unzip file.");
      }
   }
}

请注意，我按照 neoneye 的建议使用了 SSZipArchive 类。需要将 bundle 打包在某种容器中才能有效地下载所有内容，因为 bundle 只是遵循 Apple 约定的目录和文件结构。

我的一个类是一个 ViewController，它有一个标签和按钮作为 IBOutlets。 ViewController 中最重要的代码如下所示:

TestViewController.h

@interface TestViewController : UIViewController {
   UIButton *button;
   UILabel *label;
}

@property (nonatomic, retain) IBOutlet UIButton *button;
@property (nonatomic, retain) IBOutlet UILabel *label;

- (IBAction)buttonTouched:(id)sender;

@end

TestViewController.m

@implementation TestViewController
@synthesize button, label;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

// the -init method is overridden to use nib file from bundle, if bundle exists ...
- (id)init 
{
   NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
   NSString *documentsDirectory = [paths objectAtIndex:0];
   NSString *file = [documentsDirectory stringByAppendingPathComponent:@"template.bundle"];
   NSBundle *bundle = [NSBundle bundleWithPath:file];
   if (!bundle)
   {
      NSLog(@"no bundle found, falling back to default gui ...");
      return [self initWithNibName:nil bundle:nil];
   }

   NSString *nibName = NSStringFromClass([self class]);
   return [self initWithNibName:nibName bundle:bundle];
}

- (void)dealloc
{
   [button release];
   [label release];
   [view release];

   [super dealloc];
}

#pragma mark - View lifecycle

- (void)loadView
{
   if (self.nibName && self.nibBundle) 
   {
      // connect outlets to proxy objects ...
      NSDictionary *objects = [NSDictionary dictionaryWithObjectsAndKeys:
          self.label, @"label", 
          self.button, @"button", 
          nil];
      NSDictionary *proxies = [NSDictionary dictionaryWithObject:objects forKey:UINibExternalObjects];
      NSArray *nibs = [self.nibBundle loadNibNamed:self.nibName owner:self options:proxies]; // connection happens here ...

      NSLog(@"nibs found with name %@: %d", self.nibName, [nibs count]);
      return;
   }

   // show default gui if no nib was found ...

   CGRect frame = [UIScreen mainScreen].applicationFrame;
   self.view = [[[UIView alloc] initWithFrame:frame] autorelease];
   [self.view setBackgroundColor:[UIColor lightGrayColor]];

   self.button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
   [self.button setFrame:CGRectMake(0.0f, 0.0f, 60.0f, 30.0f)];
   [self.button setCenter:CGPointMake(160.0f, 100.0f)];
   [self.button addTarget:self action:@selector(buttonTouched:) forControlEvents:UIControlEventTouchUpInside];
   [self.view addSubview:self.button];

   self.label = [[[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 300.0f, 30.0f)] autorelease];
   [self.label setCenter:CGPointMake(160.0f, 50.0f)];
   [self.label setTextAlignment:UITextAlignmentCenter];
   [self.view addSubview:self.label];
}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
   [super viewDidLoad];

   // for my purposes I'll add the localized string from the mainBundle here for the standard controls, 
   // this will override the text set in the nibs, since the nibs are loaded and displayed at this point ...
   [self.button setTitle:NSLocalizedString(@"TestButton", nil) forState:UIControlStateNormal];
   [self.label setText:NSLocalizedString(@"TestLabel", nil)];

}

- (void)viewDidUnload
{
   [super viewDidUnload];
   self.button = nil;
   self.label = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

#pragma mark -

- (IBAction)buttonTouched:(id)sender 
{
   [[[[UIAlertView alloc] initWithTitle:NSLocalizedString(@"DialogTitle", nil) 
                                message:NSLocalizedString(@"ButtonTouchedText", nil) 
                               delegate:nil 
                      cancelButtonTitle:@"OK" 
                      otherButtonTitles:nil] 
     autorelease] show];
}

@end

实际的 nib 在一个单独的链接项目中定义(Cocoa NSBundle 项目更改了一些参数以使其适用于 iOS 设备)。该文件的所有者是 TestViewController，因此我可以访问所有导出和操作并进行适当的连接。请注意，在 TestViewController 中没有定义 view (UIView *) 属性，因为父类(super class)已经有一个 view 属性。确保 View 已在 Interface Builder 中连接。另请注意，为了便于使用，nib 文件使用与实际类相同的名称。

在网上找不到太多关于如何执行此操作的信息，所以我希望这对许多有类似目标的人有所帮助。