如何將字符串值從一個控制器傳遞到另一個控制器

Question

我有一個登錄控制器，成功登錄後，我想將某個字符串值傳遞給菜單頁。但是它不起作用。應用程序崩潰。 我試圖Ihuk和SAM的可能的寶貴意見，從下面的鏈接

how to pass a string value from one view controller to another view controller

loginController.h：

#import <UIKit/UIKit.h> 
@class RootViewController; 
@class Menu; 

@interface LoginController : UIViewController { 
    UIButton *login_Button; 
    UITextField *username_TextField; 
    UITextField *password_TextField; 
    RootViewController *mc1; 
    UINavigationController *navigationController; 
    Menu *mv1; 
} 

@property(nonatomic,retain) IBOutlet UIButton *login_Button; 
@property(nonatomic,retain) IBOutlet UITextField *username_TextField; 
@property(nonatomic,retain) IBOutlet UITextField *password_TextField; 
@property(nonatomic,retain) RootViewController *mc1; 
@property (nonatomic, retain) IBOutlet 
     UINavigationController *navigationController; 
@property(nonatomic,retain)Menu *mv1; 

- (IBAction)Login_Method:(id)sender; 
-(id)initWithUserName:(NSString *)name ; 
@end 

loginController.m

#import "LoginController.h" 
#import "Menu.h" 
#import "ViewController.h" 
#import "RootViewController.h" 

@implementation LoginController 

@synthesize mc1,mv1; 
@synthesize login_Button,username_TextField,password_TextField; 
@synthesize navigationController; 


// Implement viewDidLoad to do additional setup after 
// loading the view, typically from a nib. 
- (void)viewDidLoad { 
    if (![self.navigationController isNavigationBarHidden]) 
    [self.navigationController setNavigationBarHidden:YES animated:NO]; 
//[self presentModalViewController:navigationController animated:YES]; 
} 

- (void)didReceiveMemoryWarning { 
    // Releases the view if it doesn't have a superview. 
    [super didReceiveMemoryWarning]; 

    // Release any cached data, images, etc that aren't in use. 
} 

- (void)viewDidUnload { 
    // Release any retained subviews of the main view. 
    // e.g. self.myOutlet = nil; 
} 

- (IBAction)Login_Method:(id)sender 
{   
    Menu *mv2 = [[Menu alloc] initWithUserName:@"Menu" bundle:nil]; 
    //mv2.l1.text=@"aa"; //i tried this, but not work,so created initWithUserName 
    self.mv1=mv2; 
    [self presentModalViewController:mv1 animated:YES]; 
// [RootViewController release]; 
} 

-(id)initWithUserName:(NSString *)name 
{ 
    self = [super init]; 
    if (nil == self) { 
    return nil; 
    } 

    // display or store login info somewhere 
    [mv1.l1 setText:name]; 

    return self; 
} 

-(BOOL)textFieldShouldReturn:(UITextField *)theTextField { 
    [theTextField resignFirstResponder]; 
    return YES; 
} 

- (void)dealloc { 
    [username_TextField release]; 
    [password_TextField release]; 
    [super dealloc]; 
} 

@end 

Menu.h

#import <UIKit/UIKit.h> 

@class Menu; 
@interface Menu : UIViewController {  
    UILabel *l1; 
    UIButton *AccountSummary_Button; 
    UIButton *PayOffQuote_Button; 
    UIButton *PayBill_Button; 
    UIButton *Logout_Button; 
    UINavigationController *nv1; 
} 

@property(nonatomic,retain) IBOutlet UILabel *l1; 
@property(nonatomic,retain) IBOutlet UIButton *AccountSummary_Button; 
@property(nonatomic,retain) IBOutlet UIButton *PayOffQuote_Button; 
@property(nonatomic,retain) IBOutlet UIButton *PayBill_Button; 
@property(nonatomic,retain) IBOutlet UIButton *Logout_Button; 
@property (nonatomic, retain) IBOutlet UINavigationController *nv1; 

-(IBAction)ViewAccountSummary_method:(id)sender; 
-(IBAction)ViewPayOffQuote_method:(id)sender; 
-(IBAction)ViewPayBill_method:(id)sender; 
-(IBAction)Logout_method:(id)sender; 

@end 

Menu.m

Answer 1

在您的應用程序委託中創建一個屬性，例如NSString*，稱爲myString。

然後從登錄控制器和其他控制器訪問它，像這樣：

[[UIApplication sharedApplication] delegate].myString 

你可以，例如，設置在登錄控制器myString的價值：

[[UIApplication sharedApplication] delegate].myString = @"value"; 

你可以閱讀它在任何其他控制器：

NSLog(@"myString is: %@", [[UIApplication sharedApplication] delegate].myString); 

另外，一些谷碧OA風格提示：

1. 不要利用類成員（AccountSummary_Button等）
2. 不要利用類的方法（ViewAccountSummary_method等）

你應該利用的唯一的事情是類本身（ Menu等）。