在NSUserDefaults中的NSMutableArray中存储自定义对象

时间：2009-02-11 14:32:38

标签： cocoa-touch

我最近一直试图将我的iPhone应用程序的搜索结果存储在NSUserDefaults集合中。我也使用它来成功保存用户注册信息，但由于某些原因，尝试存储我的自定义位置类的NSMutableArray总是返回空。

我尝试将NSMutableArray转换为此帖子的NSData元素，但我得到了相同的结果（Possible to save an integer array using NSUserDefaults on iPhone?）

我尝试的代码示例是：

保存： 

[prefs setObject:results forKey:@"lastResults"];
[prefs synchronize];

或

NSData *data = [NSData dataWithBytes:&results length:sizeof(results)];
[prefs setObject:data forKey:@"lastResults"];

或

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:results];
[prefs setObject:data forKey:@"lastResults"];

加载 

lastResults = (NSMutableArray *)[prefs objectForKey:@"lastResults"];

或

NSData *data = [prefs objectForKey:@"lastResults"];
memcpy(&lastResults, data.bytes, data.length);

或

NSData *data = [prefs objectForKey:@"lastResults"];
lastResults = [NSKeyedUnarchiver unarchiveObjectWithData:data];

按照以下建议后，我还在我的对象中实现了NSCoder（忽略过度使用NSString的临时性）：

#import "Location.h"


@implementation Location

@synthesize locationId;
@synthesize companyName;
@synthesize addressLine1;
@synthesize addressLine2;
@synthesize city;
@synthesize postcode;
@synthesize telephoneNumber;
@synthesize description;
@synthesize rating;
@synthesize priceGuide;
@synthesize latitude;
@synthesize longitude;
@synthesize userLatitude;
@synthesize userLongitude;
@synthesize searchType;
@synthesize searchId;
@synthesize distance;
@synthesize applicationProviderId;
@synthesize contentProviderId;

- (id) initWithCoder: (NSCoder *)coder
{
    if (self = [super init])
    {
        self.locationId = [coder decodeObjectForKey:@"locationId"];
        self.companyName = [coder decodeObjectForKey:@"companyName"];
        self.addressLine1 = [coder decodeObjectForKey:@"addressLine1"];
        self.addressLine2 = [coder decodeObjectForKey:@"addressLine2"];
        self.city = [coder decodeObjectForKey:@"city"];
        self.postcode = [coder decodeObjectForKey:@"postcode"];
        self.telephoneNumber = [coder decodeObjectForKey:@"telephoneNumber"];
        self.description = [coder decodeObjectForKey:@"description"];
        self.rating = [coder decodeObjectForKey:@"rating"];
        self.priceGuide = [coder decodeObjectForKey:@"priceGuide"];
        self.latitude = [coder decodeObjectForKey:@"latitude"];
        self.longitude = [coder decodeObjectForKey:@"longitude"];
        self.userLatitude = [coder decodeObjectForKey:@"userLatitude"];
        self.userLongitude = [coder decodeObjectForKey:@"userLongitude"];
        self.searchType = [coder decodeObjectForKey:@"searchType"];
        self.searchId = [coder decodeObjectForKey:@"searchId"];
        self.distance = [coder decodeObjectForKey:@"distance"];
        self.applicationProviderId = [coder decodeObjectForKey:@"applicationProviderId"];
        self.contentProviderId = [coder decodeObjectForKey:@"contentProviderId"];
    }
}

- (void) encodeWithCoder: (NSCoder *)coder
{
    [coder encodeObject:locationId forKey:@"locationId"];
    [coder encodeObject:companyName forKey:@"companyName"];
    [coder encodeObject:addressLine1 forKey:@"addressLine1"];
    [coder encodeObject:addressLine2 forKey:@"addressLine2"];
    [coder encodeObject:city forKey:@"city"];
    [coder encodeObject:postcode forKey:@"postcode"];
    [coder encodeObject:telephoneNumber forKey:@"telephoneNumber"];
    [coder encodeObject:description forKey:@"description"];
    [coder encodeObject:rating forKey:@"rating"];
    [coder encodeObject:priceGuide forKey:@"priceGuide"];
    [coder encodeObject:latitude forKey:@"latitude"];
    [coder encodeObject:longitude forKey:@"longitude"];
    [coder encodeObject:userLatitude forKey:@"userLatitude"];
    [coder encodeObject:userLongitude forKey:@"userLongitude"];
    [coder encodeObject:searchType forKey:@"searchType"];
    [coder encodeObject:searchId forKey:@"searchId"];
    [coder encodeObject:distance forKey:@"distance"];
    [coder encodeObject:applicationProviderId forKey:@"applicationProviderId"];
    [coder encodeObject:contentProviderId forKey:@"contentProviderId"];

}

5 个答案:

答案 0 :(得分：177)

为了在数组中加载自定义对象，这就是我用来获取数组的内容：

NSUserDefaults *currentDefaults = [NSUserDefaults standardUserDefaults];
NSData *dataRepresentingSavedArray = [currentDefaults objectForKey:@"savedArray"];
if (dataRepresentingSavedArray != nil)
{
    NSArray *oldSavedArray = [NSKeyedUnarchiver unarchiveObjectWithData:dataRepresentingSavedArray];
    if (oldSavedArray != nil)
        objectArray = [[NSMutableArray alloc] initWithArray:oldSavedArray];
    else
        objectArray = [[NSMutableArray alloc] init];
}

你应该检查从用户默认值返回的数据是不是nil，因为我相信从nil取消归档会导致崩溃。

归档很简单，使用以下代码：

[[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:objectArray] forKey:@"savedArray"];

正如f3lix所指出的，您需要使自定义对象符合NSCoding协议。添加如下方法应该可以解决问题：

- (void)encodeWithCoder:(NSCoder *)coder;
{
    [coder encodeObject:label forKey:@"label"];
    [coder encodeInteger:numberID forKey:@"numberID"];
}

- (id)initWithCoder:(NSCoder *)coder;
{
    self = [super init];
    if (self != nil)
    {
        label = [[coder decodeObjectForKey:@"label"] retain];
        numberID = [[coder decodeIntegerForKey:@"numberID"] retain];
    }   
    return self;
}

答案 1 :(得分：13)

我认为你的initWithCoder方法出错了，至少在提供的代码中你没有返回'self'对象。

- (id) initWithCoder: (NSCoder *)coder
{
    if (self = [super init])
    {
        self.locationId = [coder decodeObjectForKey:@"locationId"];
        self.companyName = [coder decodeObjectForKey:@"companyName"];
        self.addressLine1 = [coder decodeObjectForKey:@"addressLine1"];
        self.addressLine2 = [coder decodeObjectForKey:@"addressLine2"];
        self.city = [coder decodeObjectForKey:@"city"];
        self.postcode = [coder decodeObjectForKey:@"postcode"];
        self.telephoneNumber = [coder decodeObjectForKey:@"telephoneNumber"];
        self.description = [coder decodeObjectForKey:@"description"];
        self.rating = [coder decodeObjectForKey:@"rating"];
        self.priceGuide = [coder decodeObjectForKey:@"priceGuide"];
        self.latitude = [coder decodeObjectForKey:@"latitude"];
        self.longitude = [coder decodeObjectForKey:@"longitude"];
        self.userLatitude = [coder decodeObjectForKey:@"userLatitude"];
        self.userLongitude = [coder decodeObjectForKey:@"userLongitude"];
        self.searchType = [coder decodeObjectForKey:@"searchType"];
        self.searchId = [coder decodeObjectForKey:@"searchId"];
        self.distance = [coder decodeObjectForKey:@"distance"];
        self.applicationProviderId = [coder decodeObjectForKey:@"applicationProviderId"];
        self.contentProviderId = [coder decodeObjectForKey:@"contentProviderId"];
    }

    return self; // this is missing in the example above


}

我用

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:results];
[prefs setObject:data forKey:@"lastResults"];

和

NSUserDefaults *currentDefaults = [NSUserDefaults standardUserDefaults];
NSData *dataRepresentingSavedArray = [currentDefaults objectForKey:@"lastResults"];
if (dataRepresentingSavedArray != nil)
{
        NSArray *oldSavedArray = [NSKeyedUnarchiver unarchiveObjectWithData:dataRepresentingSavedArray];
        if (oldSavedArray != nil)
                objectArray = [[NSMutableArray alloc] initWithArray:oldSavedArray];
        else
                objectArray = [[NSMutableArray alloc] init];
}

它对我来说非常适合。

关于，

Stefan

答案 2 :(得分：0)

请参阅“为什么NSUserDefaults无法在iPhone SDK中保存NSMutableDictionary？ “（Why NSUserDefaults failed to save NSMutableDictionary in iPhone SDK?）

如果要（自）序列化自定义对象，则必须提供（de）序列化数据的功能（NSCoding协议）。你引用的解决方案适用于int数组，因为数组不是一个对象，而是一块连续的内存块。

答案 3 :(得分：0)

我认为您的代码问题似乎不是保存结果数组。它使用

加载数据 
lastResults = [prefs arrayForKey:@"lastResults"];

这将返回键指定的数组。

答案 4 :(得分：0)

我建议不要尝试在默认数据库中存储这样的东西。

SQLite相当容易上手和使用。我在我的一个截屏视频（http://pragprog.com/screencasts/v-bdiphone）中有一集关于我写的简单包装（你可以在不购买SC的情况下获得代码）。

将应用数据存储在应用空间中会更加清晰。

所有这一切都说如果将这些数据放入默认值db仍然有意义，那么请看f3lix发布的帖子。

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