Initialize instance variables as key/value pair from NSDictionary?

Question

I have my NSObject subclass's public interface defined as,

@interface MyObject : NSObject
{
    NSString *_key1;
    NSString *_key2;
    NSString *_key3;
}
- (id)initWithDict:(NSDictionary *)dict;
@end

Is there are trick to implement the initWithDict: method so that I can pass a NSDictionary defined as

{"key1" : "value1", "key2" : "value2", "key3" : "value3"}

and the init method can set the related instance variables with their corresponding "value"?

Answer 1

You have to use KVC.

NSDictionary *dict = @{@"key1" : @"value1", @"key2" : @"value2", @"key3" : @"value3"};
for (NSString *key in [dict allKeys]) {
   [self setValue:dict[key] forKey:key];
}

Answer 2

In addition to DrummerB answer, if you have nested object like below,

@interface InnerObject : NSObject
{
    NSString *innerKey1;
}
@interface MyObject : NSObject
{
    NSString *key1;
    NSString *key2;
    NSString *key3;
    InnerObject *innerObj; 
}

You can set value to the iVar innerKey1 also by below method:

MyObject *obj = [[MyObject alloc]init];
obj.innerObj = [[InnerObject alloc]init];
[obj setValue:yourValue forKeyPath:innerObj.innerKey1];

Answer 3

You can also initialize your instance variables/properties from a dictionary like this:

[self setValuesForKeysWithDictionary:dictionary];

Here is the official Apple Documentation on setValuesForKeysWithDictionary:

https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Protocols/NSKeyValueCoding_Protocol/#//apple_ref/occ/instm/NSObject/setValuesForKeysWithDictionary: