NSMutableArray 未保存 NSUserDefault

Question

我正在尝试使用 NSUSerDefault 保存 NSMutableArray，然后打开该数组。 这里有一些代码：

-(IBAction)btnSave{    
Class *aClass = [[Class alloc]init];    
aClass.idClass=@"aaaxxx";    
aClass.nameClass=@"hello";
[myArray addObject:aClass];
NSUserDefaults *arrayDefault=[NSUserDefaults standardUserDefaults];
[arrayDefault setObject:myArray forKey:@"savedArray"];
[arrayDefault synchronize]; 
}

和

- (void)viewDidLoad
{
    [super viewDidLoad];
    myArray=[[NSMutableArray alloc]init];

    NSMutableArray *savedArray=[[NSUserDefaults standardUserDefaults]objectForKey:@"savedArray"];
    if(savedArray!=NULL){
        myArray=savedArray;
        [tableView reloadData];
    }
    // Do any additional setup after loading the view from its nib.
}

当我编译并按下按钮时，这是我在日志输出中看到的内容：

[NSUserDefaults setObject:forKey:]: Attempt to insert non-property value '(
    "<Class: 0x8452b40>"
)' of class '__NSArrayM'.  Note that dictionaries and arrays in property lists must also contain only property values

很明显，当我重新打开视图时，数组没有加载。 有什么帮助吗？

Answer 1

NSUserDefaults 只允许在其中存储 Premitive DataTypes。如果你想存储你的自定义类 Object 然后使用下面的代码，更多细节参考这个IOS Documentation

//create an array with your custom class objects

Class *aClass = [[Class alloc]init];
aClass.idClass=@"aaaxxx";
aClass.nameClass=@"hello";

[myArray addObject:aClass];

//convert your array to `NSData` object using `NSKeyedArchiver`    
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:myArray];

//store it to `NSUserDefaults`
[[NSUserDefaults standardUserDefaults] setObject:data forKey:@"myArray"];
[[NSUserDefaults standardUserDefaults] synchronize];

//convert your stored Object back to `NSData` using `NSKeyedUnarchiver`    
NSData *storedData = [[NSUserDefaults standardUserDefaults] objectForKey:@"myArray"];
NSArray *storedArr = [NSArray arrayWithArray:[NSKeyedUnarchiver unarchiveObjectWithData:storedData]];

NSLog(@"%@",storedArr[0]);

Answer 2

首先你在你的对象类中实现 NSCoding。为了保存/加载这些对象的 NSMutableArray，您可以执行以下操作：

- (void) loadArray {
    //Loading the NSMutableArray
    NSData *arrayData = [[NSUserDefaults standardUserDefaults] objectForKey:@"ArrayKey"];
    myArray = [NSKeyedUnarchiver arrayData];
}

-(void) saveArray {
    //Saving the NSMutableArray
    NSData *arrayData = [NSKeyedArchiver archivedDataWithRootObject:myArray];
    [[NSUserDefaults standardUserDefaults] setObject:arrayData forKey:@"ArrayKey"];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

有关更多信息，我建议查看更长的教程。例如 Ray Wenderlich 的 How to Save your App Data with NSCoding And NSFileManager 就是一个很好的。

Answer 3

您需要在模型对象Class 中实现 NSCoding 协议。需要对非标准数据进行序列化和反序列化到NSUserDefaults。

现在您可以使用NSKeyedArchiver 将对象转换为数据并存储在 userDefaults 中。使用NSKeyedUnarchiver 将数据从默认值转换回对象。

//h file
@interface Class : NSObject<NSCoding>

@property (nonatomic, copy) NSString *idClass;
@property (nonatomic, copy) NSString *nameClass;


//m File

- (void)encodeWithCoder:(NSCoder *)aCoder{

    [aCoder encodeObject:self.idClass forKey:@"IDClass"];
    [aCoder encodeObject:self.nameClass forKey:@"NameClass"];

}

- (id)initWithCoder:(NSCoder *)aDecoder{

    self = [super init];

    if (self) {
        self.idClass = [aDecoder decodeObjectForKey:@"IDClass"];
        self.nameClass = [aDecoder decodeObjectForKey:@"NameClass"];
    }

    return self;
}

实施 NSCoding 后，您可以将它们归档以存储为 userDefaults 中的数据

//Saving array
Class *aClass = [[Class alloc]init];    
aClass.idClass=@"aaaxxx";    
aClass.nameClass=@"hello";

[myArray addObject:aClass];

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:myArray];

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
[defaults setObject:data forKey:@"savedArray"];
[defaults synchronize]; 

//Retrieving 

NSData *data = [defaults objectForKey:@"savedArray"];
NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:data];