在NSUserDefaults中的NSMutableArray中存储自定义对象

我最近一直在尝试将iPhone应用程序的搜索结果存储在NSUserDefaults集合中。我还使用它成功保存了用户注册信息，但是由于某种原因，尝试存储自定义Location类的NSMutableArray总是空着。

截至本文发布之时，我尝试将NSMutableArray转换为NSData元素，但得到的结果相同（可以在iPhone上使用NSUserDefaults保存整数数组吗？）

我尝试过的代码示例是：

保存：

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

要么

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

要么

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

加载：

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

要么

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

要么

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

在遵循以下建议之后，我还在我的对象中实现了NSCoder（忽略对NSString的临时使用）：

#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"];

}

为了在数组中加载自定义对象，这是我用来获取数组的方法：

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];
}

您应该检查从用户默认值返回的数据是否不是nil，因为我认为从nil取消存档会导致崩溃。

归档很简单，使用以下代码：

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

正如f3lix指出的那样，您需要使您的自定义对象符合NSCoding协议。添加如下所示的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;
}

我认为您的initWithCoder方法出错，至少在提供的代码中，您没有返回“自我”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];
}

它对我来说很完美。

带着敬意，

斯特凡

我认为您的代码似乎没有保存结果数组的问题。其加载数据尝试使用

lastResults = [prefs arrayForKey:@"lastResults"];

这将返回键指定的数组。

请参阅“为什么NSUserDefaults无法在iPhone SDK中保存NSMutableDictionary？”（为什么NSUserDefaults无法在iPhone SDK中保存NSMutableDictionary？）

如果要对自定义对象进行（反序列化），则必须提供对数据进行（反序列化）功能（NSCoding协议）。您引用的解决方案适用于int数组，因为该数组不是对象，而是连续的内存块。

我建议不要尝试将此类内容存储在默认数据库中。

SQLite相当容易使用。在我的一个截屏视频（http://pragprog.com/screencasts/v-bdiphone）中有一集关于我编写的简单包装的一集（您无需购买SC即可获得代码）。

在应用程序空间中存储应用程序数据要干净得多。

所有这些表明，如果仍然可以将此数据放入默认数据库，请参阅f3lix发布。