iPhone SDK：NSUserDefaults無法正常工作

Question

爲了全局操作的目的，我已經在應用程序委託中聲明瞭一些字符串屬性。

問題是寫入的值與正在讀取的值不同。當我將調試消息打印出來時，它就是我們熟悉的數據。它幾乎看起來像被緩存。

代碼聲明：NSUserDefaults的與

//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; 

加載全局變量：

[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."); 
} 

代碼來設置全局變量回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

當你正在使用的ivars而不是你聲明的屬性，我猜你的對象在你設置它們之前就已經被釋放了。然而，因爲你沒有崩潰，它可能是別的東西。

試試這個：

[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."); 
} 

這

[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"]; 
// ... 

在一般情況下，如果你聲明的屬性，它的更新/讀取值時使用的getter和setter方法是一個好主意。