Swift 3更新

func setObject(value:AnyObject ,key:String)
{
    let pref = UserDefaults.standard
    pref.set(value, forKey: key)
    pref.synchronize()
}

func getObject(key:String) -> AnyObject
{
    let pref = UserDefaults.standard
    return pref.object(forKey: key)! as AnyObject
}

在Swift5和Xcode 10.2中

//Save
UserDefaults.standard.set(true, forKey: "Key1") //Bool
UserDefaults.standard.set(1, forKey: "Key2")  //Integer
UserDefaults.standard.set("This is my string", forKey: "Key3") //String
UserDefaults.standard.synchronize()
        
//Retrive
UserDefaults.standard.bool(forKey: "Key1")
UserDefaults.standard.integer(forKey: "Key2")
UserDefaults.standard.string(forKey: "Key3")
            
//Remove
UserDefaults.standard.removeObject(forKey: "Key3")

注意:保存文本数据(意味着字符串，数组，字典等)在UserDefaults。

不要将图片保存在UserDefaults中，不推荐(保存图片在本地目录)。

就像这样:

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

// saving an NSString
[prefs setObject:@"TextToSave" forKey:@"keyToLookupString"];

然后检索:

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

// getting an NSString
NSString *myString = [prefs stringForKey:@"keyToLookupString"];

你应该看看苹果的NSUserDefaults类参考，也可以看看这个教程:iPhone编程教程-使用NSUserDefaults保存/检索数据

更准确地说

-(void)saveToUserDefaults:(NSString*)myString
{
    NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];

    if (standardUserDefaults) {
        [standardUserDefaults setObject:myString forKey:@"timestamps"];
        [standardUserDefaults synchronize];
    }
}

用于保存:

[[NSUserDefaults standardUserDefaults]setObject:@"YES" forKey:@"KTerminated"];
[[NSUserDefaults standardUserDefaults]synchronize];

对于检索使用这个:

[[[NSUserDefaults standardUserDefaults]stringForKey:@"KTerminated"] isEqualToString:@"YES"];

-(void)saveToUserDefaults:(NSString*)string_to_store keys:(NSString *)key_for_the_String
{
    NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];

    if (standardUserDefaults) {
        [standardUserDefaults setObject:string_to_store forKey:key_for_the_String];
        [standardUserDefaults synchronize];
    }
}

叫它:

[self saveToUserDefaults:@"string_to_store" : @"key_for_the_string"];

使用以下方法检索字符串:

NSString * stored_string = [[NSUserDefaults standardUserDefaults] stringforkey:key_for_the_String]