持久化 轻量数据

今天在使用NSUserDefault的时候报错Attempt to insert non-property value .... of class。

原因是：我存储的是自定义对象，而NSUserDefault只支持部分内置对象的存储。

解决办法：

Here is one example per request:



Save:



NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

NSMutableArray *arr = ... ; // set value

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:arr];

[defaults setObject:data forKey:@"theKey"];


Load:



NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

NSData *data = [defaults objectForKey:@"theKey"];

NSArray *arr = [NSKeyedUnarchiver unarchiveObjectWithData:data];

The element in the array implements



@interface CommentItem : NSObject<NSCoding> {

    NSString *value;

}

Then in the implementation of CommentItem, provides two methods:



-(void)encodeWithCoder:(NSCoder *)encoder

{

    [encoder encodeObject:value forKey:@"Value"];

}



-(id)initWithCoder:(NSCoder *)decoder

{

    self.value = [decoder decodeObjectForKey:@"Value"];

    return self;

}