iPhone SDK：NSUserDefaults无法正常工作

Question

为了全局操作的目的，我已经在应用程序委托中声明了一些字符串属性。

问题是写入的值与正在读取的值不同。当我将调试消息打印出来时，它就是我们熟悉的数据。它几乎看起来像被缓存。

代码声明：NSUserDefaults的与

//globals 
    NSUserDefaults *options; 
    NSString *strUserLogin; 
    NSString *strTransKey; 
    NSString *strBizName; 
    NSString *strSwitchTesting; 
    NSString *strDate; 
    NSString *strTotalAmount; 
    NSString *strTopMessage; 
    NSString *strBottomMessage; 
    NSString *strTransType; 
    NSString *strMerchantName; 
    NSString *strCustomerEmail; 
    NSString *strMerchantEmail; 

@property(nonatomic,retain) NSUserDefaults *options; 
@property(nonatomic,retain) NSString *strUserLogin; 
@property(nonatomic,retain) NSString *strTransKey; 
@property(nonatomic,retain) NSString *strBizName; 
@property(nonatomic,retain) NSString *strSwitchTesting; 
@property(nonatomic,retain) NSString *strDate; 
@property(nonatomic,retain) NSString *strTotalAmount; 
@property(nonatomic,retain) NSString *strTopMessage; 
@property(nonatomic,retain) NSString *strBottomMessage; 
@property(nonatomic,retain) NSString *strTransType; 
@property(nonatomic,retain) NSString *strMerchantName; 
@property(nonatomic,retain) NSString *strCustomerEmail; 
@property(nonatomic,retain) NSString *strMerchantEmail; 

加载全局变量：

[NSUserDefaults resetStandardUserDefaults]; 
options = [NSUserDefaults standardUserDefaults]; 
if(options) 
{ 
    strUserLogin = [options stringForKey:@"UserLogin"]; 
    strTransKey = [options stringForKey:@"TransKey"]; 
    strBizName = [options stringForKey:@"BizName"];  
    strSwitchTesting =[options stringForKey:@"SwitchTesting"];  
    //str date 
    //total amount 
    strTopMessage =[options stringForKey:@"MessageTop"]; 
    strBottomMessage =[options stringForKey:@"MessageBottom"]; 
    //trans type 
    strMerchantName = [options stringForKey:@"BizName"]; 
    //customer email 
    strMerchantEmail =[options stringForKey:@"MerchantEmail"]; 
} 
else { 
    NSLog(@"applicationDidFinishLaunching: Error reading config file."); 
} 

代码来设置全局变量回NSUserDefaults的：

//save to disk preferences 
    [options setObject: txtUserLogin.text forKey:@"UserLogin"]; 
    [options setObject: txtTransKey.text forKey:@"TransKey"]; 
    [options setObject: txtBizName.text forKey:@"BizName"]; 
    [options setObject: txtMerchantEmail.text forKey:@"MerchantEmail"]; 
    [options setObject:txtMsgTop.text forKey:@"MessageTop"]; 
    [options setObject:txtMsgBottom.text forKey:@"MessageBottom"]; 
    if(switchTesting.on) 
    { 
     [options setObject:@"ON" forKey:@"SwitchTesting"]; 
    } 
    else 
    { 
     [options setObject:@"OFF" forKey:@"SwitchTesting"]; 
    } 

    //this is the magic sauce 
    [options synchronize]; 

Answer 1

当你正在使用的ivars而不是你声明的属性，我猜你的对象在你设置它们之前就已经被释放了。然而，因为你没有崩溃，它可能是别的东西。

试试这个：

[NSUserDefaults resetStandardUserDefaults]; 
self.options = [NSUserDefaults standardUserDefaults]; 
if(options) 
{ 
    self.strUserLogin = [options stringForKey:@"UserLogin"]; 
    self.strTransKey = [options stringForKey:@"TransKey"]; 
    self.strBizName = [options stringForKey:@"BizName"];  
    // You get the idea. 
} 
else { 
    NSLog(@"applicationDidFinishLaunching: Error reading config file."); 
} 

这

[self.options setObject: txtUserLogin.text forKey:@"UserLogin"]; 
[self.options setObject: txtTransKey.text forKey:@"TransKey"]; 
[self.options setObject: txtBizName.text forKey:@"BizName"]; 
[self.options setObject: txtMerchantEmail.text forKey:@"MerchantEmail"]; 
// ... 

在一般情况下，如果你声明的属性，它的更新/读取值时使用的getter和setter方法是一个好主意。