如何在不丟失目標控制器中的數據的情況下打開模態視圖？

Question

問題是我不知道如何在推送或呈現爲模態視圖後保存接收到的控制器數據。我正在使用故事板，ARC，iOS5。當項目使用xib時，一切正常。我在目標ViewController中有UIWebView，我需要它爲twitter OAuth身份驗證打開傳輸的URL。這裏是TweetViewController的代碼，我從那裏調用WebViewController的函數。然後我嘗試在UIWebController所在的位置展示UIViewController。但是在我傳輸url之後，它忘記了這個數據。所以在ViewDidLoad函數中，NSURL爲空。

// TweetViewController.h 
#import <UIKit/UIKit.h> 
#import "RSTwitterEngine.h" 
#import "WebViewController.h" 

@interface TweetViewController : UIViewController <RSTwitterEngineDelegate, WebViewControllerDelegate> 

@property (strong, nonatomic) RSTwitterEngine *twitterEngine; 
@property (strong, nonatomic) WebViewController *leWebView; 

@property (unsafe_unretained, nonatomic) IBOutlet UITextView *textView; 
@property (unsafe_unretained, nonatomic) IBOutlet UIBarButtonItem *sendButton; 
@property (unsafe_unretained, nonatomic) IBOutlet UILabel *statusLabel; 

- (IBAction)sendTweet:(id)sender; 
- (void)swipedRight:(UIGestureRecognizer *)recognizer; 

@end 

部分TweetViewController.m的它發送URL數據：所以在這裏

#pragma mark - RSTwitterEngine Delegate Methods 

- (void)twitterEngine:(RSTwitterEngine *)engine needsToOpenURL:(NSURL *)url 
{ 
    self.leWebView = [_leWebView initWithURL:url]; 
    self.leWebView.delegate = self; 
    [self performSegueWithIdentifier:@"LeWebSegue" sender:self];  
    //[self presentModalViewController:self.leWebView animated:YES]; 
} 

是WebViewController關鍵部分：

// WebViewController.h 

#import <UIKit/UIKit.h> 

@protocol WebViewControllerDelegate; 

@interface WebViewController : UIViewController <UIWebViewDelegate> 

@property (retain, nonatomic) NSURL *currentURL; 

@property (assign, nonatomic) id <WebViewControllerDelegate> delegate; 
@property (retain, nonatomic) IBOutlet UIWebView *leWebView; 
@property (retain, nonatomic) IBOutlet UIActivityIndicatorView *leActivityIndicator; 

- (id)initWithURL:(NSURL *)url; 
- (IBAction)ActionNoMore:(id)sender; 
@end 

@protocol WebViewControllerDelegate <NSObject> 

- (void)dismissWebView; 
- (void)handleURL:(NSURL *)url; 

@end 

和WebViewController.m

#import "WebViewController.h" 
#import "AppDelegate.h" 

@implementation WebViewController 

@synthesize delegate = _delegate; 
@synthesize currentURL = _currentURL; 
@synthesize leWebView = _leWebView; 
@synthesize leActivityIndicator = _leActivityIndicator; 

#pragma mark - Initialization 
// ======= Here is that function which recieves url ======== 
- (id)initWithURL:(NSURL *)url 
{ 
    self = [self.storyboard instantiateViewControllerWithIdentifier:@"WebView"]; 
    NSLog(@"WebViewController initWithURL called. Recieved url = %@", url); 

    if (self) { 
     self.currentURL = url; 
     self.delegate = nil; 
    } 

    return self; 

} 

#pragma mark - View Lifecycle 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    NSLog(@"WebViewController viewDidLoad called. currentURL = %@", self.currentURL); 

    self.leWebView.scalesPageToFit = YES; 
    [self.leWebView loadRequest:[NSURLRequest requestWithURL:self.currentURL]];  
} 

- (void)viewDidUnload 
{ 
    [self setLeWebView:nil]; 
    [self setLeActivityIndicator:nil]; 

    [super viewDidUnload]; 
} 

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

#pragma mark - UIWebView Delegate Methods 

- (BOOL)LeWebView:(UIWebView *)LeWebView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType 
{ 
    if ([request.URL.scheme isEqualToString:@"rstwitterengine"] && (self.delegate)) { 
     if (self.leActivityIndicator) [self.leActivityIndicator stopAnimating]; 
     [self.delegate handleURL:request.URL]; 
     return NO; 
    } else { 
     return YES; 
    } 
} 

- (void)webViewDidStartLoad:(UIWebView *)LeWebView 
{ 
    if (self.leActivityIndicator) [self.leActivityIndicator startAnimating]; 
} 

- (void)webViewDidFinishLoad:(UIWebView *)LeWebView 
{ 
    if (self.leActivityIndicator) [self.leActivityIndicator stopAnimating]; 
} 

- (void)LeWebView:(UIWebView *)LeWebView didFailLoadWithError:(NSError *)error 
{ 
    if (self.leActivityIndicator) [self.leActivityIndicator stopAnimating]; 

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" 
                message:[error localizedDescription] 
                delegate:nil 
              cancelButtonTitle:@"Dismiss" 
              otherButtonTitles:nil]; 
    [alert show]; 
} 

#pragma mark - Custom Methods 


- (IBAction)ActionNoMore:(id)sender { 
    if (self.delegate) [self.delegate dismissWebView]; 

} 
@end 

在所有，當我嘗試加載該視圖，我收到日誌消息，WebViewController viewDidLoad調用。 currentURL =（null）

Answer 1

我注意到的一點是，您正在調用故事板以在initWithURL方法中創建視圖控制器。創建對象的正常方式是執行一次alloc，然後執行initWithURL。 alloc方法在內存中創建對象，initWithURL配置對象。如果您正在調用alloc，然後在initWithURL中調用instantiateViewControllerWithIdentifier，則可能會創建內存泄漏，因爲instantiateViewControllerWithIdentifier在調用它時也分配內存。然後你將「自我」設置爲另一個地址。

當您運行instantiateViewControllerWithIdentifier時，這可能會造成混淆。這很難說。您應該在父視圖控制器中運行instantiateViewControllerWithIdentifier，然後推送您的視圖控制器，然後設置您的URL，因爲UIWebViews僅在顯示時才實例化，而不是在創建視圖控制器時實例化。

HTH