IOS 如何持久化自定义对象（使用NSUserDefaults）

如果持久话自定义对象那么这个对象一定要遵循 NSCoding协议并实现编解码；然后再将编解码后的数据 NSKeyedArchiver 到NSData中

@interface NSKeyAndValue : NSObject<NSCoding>// 键值对象
@property (nonatomic, retain) NSString* m_strKey;
@property (nonatomic, retain) NSString* m_strValue;
@property (nonatomic, retain) NSString* m_strID;
@end

@implementation NSKeyAndValue
@synthesize m_strKey,m_strValue, m_strID;
- (void)encodeWithCoder:(NSCoder *)aCoder{
[aCoder encodeObject:self.m_strKey forKey:@"m_strKey"];
[aCoder encodeObject:self.m_strValue forKey:@"m_strValue"];
[aCoder encodeObject:self.m_strID forKey:@"m_strID"];
}

- (id)initWithCoder:(NSCoder *)aDecoder{
self = [super init];
if (self) {
self.m_strKey = [aDecoder decodeObjectForKey:@"m_strKey"];
self.m_strValue = [aDecoder decodeObjectForKey:@"m_strValue"];
self.m_strID = [aDecoder decodeObjectForKey:@"m_strID"];
}
return self;
}

读取和保存自定义对象方式如下：

- (void)readMsgDataToMemory
{
NSString *key = @"mydata";
NSData *prevSavedData = [[NSUserDefaults standardUserDefaults] objectForKey:key];
NSMutableDictionary *decodedSingleObj = (NSMutableDictionary *)[NSKeyedUnarchiver unarchiveObjectWithData:prevSavedData];
[creatGroupInviterDictionary setDictionary:decodedSingleObj];
}

- (void)constantStoreOfflineSystemData
{
if ([creatGroupInviterDictionary.allKeys count] > 0)
{
NSString *key = @"mydata";
NSData *encodedSingleObj = [NSKeyedArchiver archivedDataWithRootObject:creatGroupInviterDictionary];
[[NSUserDefaults standardUserDefaults] setObject:encodedSingleObj forKey:key];
[[NSUserDefaults standardUserDefaults] synchronize];
}
}

creatGroupInviterDictionary 是存储 NSKeyAndValue 对象的键值对

转自：http://lu-ping-yin.blog.163.com/blog/static/416199920147113210728/