Best way to save app data with kind of relationships

Question

I'm trying to implement persistence for a simple data model of an iOS app. It's kind of a database, but with a small amount of data (200-500 entries). I think core data is no option here.

The data model looks somehow like this (currently I use NSDictionary with NSArray):

// Note: NSStrings and NSNumbers are simplified for readability (no @)
@{ "Companys" : @[
          @{ "ID"           : 1,
             "Company name" : "ABC Inc.",
             "Website"      : "http://www.abc.com"
           },
          @{ "ID"           : 2,
             "Company name" : "XYZ Inc.",
             "Website"      : "http://www.xyz.com"
           },
          @{ "ID"           : 3,
             "Company name" : "123 Inc.",
             "Website"      : "http://www.123.net"
           },
          // ... about 90 companies
          ],
    "Employees": @[
          @{ "ID"           : 1,
             "First name"   : "John",
             "Last name"    : "Doe"
           },
          @{ "ID"           : 2,
             "First name"   : "David",
             "Last name"    : "Green"
           },
          // ... about 500 employees
    ]
}

Now I'm facing the problem of relationships (which employees work in which company). I thought of adding and NSArray to the company NSDictionary which holds the IDs of the employees of that company. But somehow I'm afraid of bad performance as I would need to enumerate all companies each time I want to get the company which an employee works for.

Is there any better solutions for saving this kind of data? I think using SQLite or Core Data would be way to over-engineered and would cost too much development time...

EDIT: Please don't suggest Core Data in your comments and answers. Core Data is not an option as the data is very static with only few changes, and sorting is not needed. Also iCloud synchronization might be an option. Core Data has plenty of bugs when using iCloud...

Answer 1

Core Data is cool, don't be afraid of it :) And I suggest you to use Core Data.

But if you don't want to learn modern technology which is popularized by Apple, you should to save your data in plist-files. There are many tutorials, here is nice sample.

Answer 2

If your database is too small for Core Data, maybe NSCoding will work for you. I don't recommend storing your data in dictionaries and arrays (at runtime). Instead (since your data model is not too complex) implement model objects such as Employee and Company. These model objects should then implement the NSCoding protocol. It could look something like this:

@interface Employee : NSObject <NSCoding>
@property (nonatomic) NSString *firstName;
@property (nonatomic) NSString *lastName;
@property (nonatomic, weak) Company *company;
@end

@implementation Employee
- (id)initWithCoder:(NSCoder *)coder {
    self = [super init];
    if (self) {
        self.firstName = [coder decodeObjectForKey:@"FirstName"];
        self.lastName = [coder decodeObjectForKey:@"LastName"];
        self.company = [coder decodeObjectForKey:@"Company"];
    }
}
- (void)encodeWithCoder:(NSCoder *)coder {
    [coder encodeObject:self.firstName forKey:@"FirstName"];
    [coder encodeObject:self.lastName forKey:@"LastName"];
    [coder encodeConditionalObject:self.company forKey:@"Company"];
}
@end

@interface Company : NSObject <NSCoding>
@property (nonatomic) NSString *name;
@property (nonatomic) NSString *website;
@property (nonatomic) NSArray *employees;
@end

@implementation Company
- (id)initWithCoder:(NSCoder *)coder {
    self = [super init];
    if (self) {
        self.name = [coder decodeObjectForKey:@"Name"];
        self.website = [coder decodeObjectForKey:@"Website"];
        self.employees = [coder decodeObjectForKey:@"Employees"];
    }
}
- (void)encodeWithCoder:(NSCoder *)coder {
    [coder encodeObject:self.name forKey:@"Name"];
    [coder encodeObject:self.website forKey:@"Website"];
    [coder encodeObject:self.employees forKey:@"Employees"];
}
@end

Now you can simply store everything with an NSKeyedArchiver:

[NSKeyedArchiver archiveRootObject:companiesArray toFile:somePath];

And load them with an NSKeyedUnarchiver:

NSArray *companiesArray = [NSKeyedUnarchiver unarchiveObjectWithFile:somePath];