ios - iOS 中自动保存标签和开关信息

Question

我对开发 iDevice 应用程序还比较陌生。经过在互联网上进行广泛搜索后，我最终得到了一个没有答案的问题。

我正在开发一个“笔记应用程序”，用户可以在文本字段中输入信息，打开开关，然后有机会完全退出应用程序，重新打开，并且信息仍然存在。没有“保存”按钮。这可能吗？也许有一个“重置”按钮来丢弃所有信息。

我目前使用的是 Xcode 4.5。有聪明的 xcoder 可以给我提示吗？

我们将不胜感激所有帮助!

编辑

我使用了保存/加载功能，但发生了一些奇怪的事情。发生的情况是，当我在每个文本字段(我有十二个)中输入内容时，点击“保存”，然后退出应用程序。当我重新打开应用程序并点击“从文本字段 12 加载”文本时，会在文本字段 1 中加载文本。所有其他文本都消失了。有人知道吗？

这是代码，供有时间的人使用。

SecondViewController.h

@interface SecondViewController : UIViewController <UITextFieldDelegate> {

    IBOutlet UITextField *myTextField;
    IBOutlet UITextField *myTextField2;
    IBOutlet UITextField *myTextField3;
    IBOutlet UITextField *myTextField4;
    IBOutlet UITextField *myTextField5;
    IBOutlet UITextField *myTextField6;
    IBOutlet UITextField *myTextField7;
    IBOutlet UITextField *myTextField8;
    IBOutlet UITextField *myTextField9;
    IBOutlet UITextField *myTextField10;
    IBOutlet UITextField *myTextField11;
    IBOutlet UITextField *myTextField12;
    
    IBOutlet UILabel *loaded; }

-(IBAction)save:(id)sender;
-(IBAction)load:(id)sender;

SecondViewController.m

@implementation SecondViewController

-(IBAction)save:(id)sender{
    
    //First Save String
    NSString *savestring =myTextField.text;
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:savestring forKey:@"saveString"];
    [defaults synchronize];
    
    //Second Save String
    NSString *savestring2 =myTextField2.text;
    NSUserDefaults *defaults2 = [NSUserDefaults standardUserDefaults];
    [defaults2 setObject:savestring2 forKey:@"saveString2"];
    [defaults2 synchronize];
    
    //Third Save String
    NSString *savestring3 =myTextField3.text;
    NSUserDefaults *defaults3 = [NSUserDefaults standardUserDefaults];
    [defaults3 setObject:savestring3 forKey:@"saveString3"];
    [defaults3 synchronize];
    
    //Fourth Save String
    NSString *savestring4 =myTextField4.text;
    NSUserDefaults *defaults4 = [NSUserDefaults standardUserDefaults];
    [defaults4 setObject:savestring4 forKey:@"saveString4"];
    [defaults4 synchronize];
    
    //Fifth Save String
    NSString *savestring5 =myTextField5.text;
    NSUserDefaults *defaults5 = [NSUserDefaults standardUserDefaults];
    [defaults5 setObject:savestring5 forKey:@"saveString5"];
    [defaults5 synchronize];
    
    //Sixth Save String
    NSString *savestring6 =myTextField6.text;
    NSUserDefaults *defaults6 = [NSUserDefaults standardUserDefaults];
    [defaults6 setObject:savestring6 forKey:@"saveString6"];
    [defaults6 synchronize];
    
    //Seventh Save String
    NSString *savestring7 =myTextField7.text;
    NSUserDefaults *defaults7 = [NSUserDefaults standardUserDefaults];
    [defaults7 setObject:savestring7 forKey:@"saveString7"];
    [defaults7 synchronize];
    
    //Eight Save String
    NSString *savestring8 =myTextField8.text;
    NSUserDefaults *defaults8 = [NSUserDefaults standardUserDefaults];
    [defaults8 setObject:savestring8 forKey:@"saveString8"];
    [defaults8 synchronize];
    
    //Ninth Save String
    NSString *savestring9 =myTextField9.text;
    NSUserDefaults *defaults9 = [NSUserDefaults standardUserDefaults];
    [defaults9 setObject:savestring9 forKey:@"saveString9"];
    [defaults9 synchronize];
    
    //Tenth Save String
    NSString *savestring10 =myTextField10.text;
    NSUserDefaults *defaults10 = [NSUserDefaults standardUserDefaults];
    [defaults10 setObject:savestring10 forKey:@"saveString10"];
    [defaults10 synchronize];
    
    //Eleventh Save String
    NSString *savestring11 =myTextField11.text;
    NSUserDefaults *defaults11 = [NSUserDefaults standardUserDefaults];
    [defaults11 setObject:savestring11 forKey:@"saveString11"];
    [defaults11 synchronize];
    
    //Twelvth Save String
    NSString *savestring12 =myTextField12.text;
    NSUserDefaults *defaults12 = [NSUserDefaults standardUserDefaults];
    [defaults12 setObject:savestring12 forKey:@"saveString12"];
    [defaults12 synchronize];
    
    loaded.text = @"Dine notater ble lagret!"; }
-(IBAction)load:(id)sender;{
    
    //First Load String
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *loadstring = [defaults objectForKey:@"saveString"];
    [myTextField setText:loadstring];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Second Load String
    NSUserDefaults *defaults2 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring2 = [defaults2 objectForKey:@"saveString2"];
    [myTextField setText:loadstring2];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Third Load String
    NSUserDefaults *defaults3 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring3 = [defaults3 objectForKey:@"saveString3"];
    [myTextField setText:loadstring3];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Forth Load String
    NSUserDefaults *defaults4 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring4 = [defaults4 objectForKey:@"saveString4"];
    [myTextField setText:loadstring4];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Fifth Load String
    NSUserDefaults *defaults5 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring5 = [defaults5 objectForKey:@"saveString5"];
    [myTextField setText:loadstring5];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Sixth Load String
    NSUserDefaults *defaults6 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring6 = [defaults6 objectForKey:@"saveString6"];
    [myTextField setText:loadstring6];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Seventh Load String
    NSUserDefaults *defaults7 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring7 = [defaults7 objectForKey:@"saveString7"];
    [myTextField setText:loadstring7];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Eight Load String
    NSUserDefaults *defaults8 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring8 = [defaults8 objectForKey:@"saveString8"];
    [myTextField setText:loadstring8];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Ninth Load String
    NSUserDefaults *defaults9 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring9 = [defaults9 objectForKey:@"saveString9"];
    [myTextField setText:loadstring9];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Tenth Load String
    NSUserDefaults *defaults10 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring10 = [defaults10 objectForKey:@"saveString10"];
    [myTextField setText:loadstring10];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Eleventh Load String
    NSUserDefaults *defaults11 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring11 = [defaults11 objectForKey:@"saveString11"];
    [myTextField setText:loadstring11];
    [loaded setText:@"Dine notater ble lastet inn!"];
    
    //Twelvth Load String
    NSUserDefaults *defaults12 = [NSUserDefaults standardUserDefaults];
    NSString *loadstring12 = [defaults12 objectForKey:@"saveString12"];
    [myTextField setText:loadstring12];
    [loaded setText:@"Dine notater ble lastet inn!"];

}

对于那些非挪威人! “请在最后的客栈用餐!”和“请吃饭!”表示保存并加载。

再次强调，如果有人有时间查看这些内容，我将不胜感激!

Answer 1

您需要一个实现 UITextFieldDelegate 的类协议(protocol)并将其设置为文本字段的委托(delegate)属性的值。在委托(delegate)中，您想要实现 textFieldDidEndEditing: 方法，并在该方法中将文本字段的值写入磁盘。我所说的“磁盘”是指一些持久存储，例如 .plist 文件或 SQLite 数据库，甚至只是文本文件。在应用委托(delegate)的 -applicationDidFinishLaunching:withOptions: 方法中，您想要检查此文件是否存在，如果存在，则读取它以确定如何预填充文本字段。

这是一个非常简单的答案，但这就是它的要点，而不是为您编写整个功能。随着您获得更多知识，您可以在此基础上进行构建(例如，实现 textField:shouldChangeCharactersInRange:replacementString: 并使用计时器来保存用户的进度，即使他们没有退出文本字段等)。