从 UIViewController 更改 AppDelegate 的属性不起作用 [英] Change property of AppDelegate from UIViewController is not working

问题描述

我遇到了一个问题，即在 AppDelegate 内部，我创建了一个属性以在应用程序内共享值.

I run into an issue that inside of AppDelegate, I create a property to share value within the app.

@property (nonatomic, retain) User *currentUser;

User 对象的定义是

@property int points;
@property (nonatomic, copy) NSString *userName;

我有一个 UIViewController A，其中有一个显示当前用户名的字段.单击一个按钮将显示 UIViewController B 和 UIVIewController B 内部，我尝试更改值:

I have a UIViewController A with a field displaying current user's name. Click on a button will bring up UIViewController B and inside of UIVIewController B, I try to change the values:

// I print out these two values here 1
((AppDelegate*)[UIApplication sharedApplication].delegate).currentUser.userName= @"newName" ;
((AppDelegate*)[UIApplication sharedApplication].delegate).currentUser.points= 19 ;
// I print out these two values here 2

从 1 和 2 的打印结果来看，userName 已成功更改.但是，当我将控件从 B 传递回 A 时，UIViewController A 中的 userName 字段尚未更新.在我的 ViewController A 中，我有:

From the print out at 1 and 2, the userName has been changed successfully. However, when I pass the control back to A from B, the userName field in UIViewController A has not been updated. In my ViewController A, I have:

- (void)viewWillAppear:(BOOL)animated{
   textField.text = ((AppDelegate*)[UIApplication sharedApplication].delegate).currentUser.userName;
}

有什么想法吗?

问候锤子

更奇怪的是，第一行打印 0，第二行 13，第三行 0 和最后一行 13.看起来这个赋值永远不会起作用.用户 ID 定义为 @property int userId;.

it is more weird that, the first line prints 0, second line 13, 3rd line 0 and the last line 13. It looks like the assignment never works. User ID is defined as @property int userId;.

NSLog(@"BeforeLogin:%d",((AppDelegate*)[UIApplication sharedApplication].delegate).currentUser.userId);
NSLog(@"newUser.userId:%d",newUser.userId);
// update profile locally
((AppDelegate*)[UIApplication sharedApplication].delegate).currentUser.userId= newUser.userId ;
NSLog(@"AfterLogin:%d",((AppDelegate*)[UIApplication sharedApplication].delegate).currentUser.userId);
NSLog(@"newUser.userToken:%@",newUser.userToken);

用户.h

#import <Foundation/Foundation.h>
@interface User : NSObject<HttpClientDelegate>
@property int userId; // I also try @property (assign, nonatomic, readwrite) int userId;

推荐答案

你应该改变你的属性定义，例如，

you should change your property definition e.g.,

这个

@property (nonatomic, copy) NSString *userName;

有了这个

@property (nonatomic, strong) NSString *userName;

另请查看如何定义属性

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