Menu
I have an object called Settings that inherits from NSMutableDictionary. When I try to initialize this object using
Settings *settings = [[Settings alloc] initWithContentsOfFile: @"someFile"]
it returns an object of type NSCFDictionary. As a result, it doesn't recognize my additional methods. For example, when I call the selector "save", it objects:
[NSCFDictionary save]: unrecognized selector sent to instance 0x524bc0
Of course, it's OK when I initialize using the garden variety
Settings *settings = [[Settings alloc] init]
I tried to cast it again to Settings but that didn't work. This seems really simple - what am I missing?
Thanks
230
Use -mutableCopy . NSDictionary *d; NSMutableDictionary *m = [d mutableCopy]; Note that -mutableCopy returns id ( Any in Swift) so you will want to assign / cast to the right type. It creates a shallow copy of the original dictionary.
An object representing a static collection of key-value pairs, for use instead of a Dictionary constant in cases that require reference semantics.
[myDictionary setObject:nextValue forKey:myWord]; You can simply say: myDictionary[myWord] = nextValue; Similarly, to get a value, you can use myDictionary[key] to get the value (or nil).
The NSMutableDictionary class declares the programmatic interface to objects that manage mutable associations of keys and values. It adds modification operations to the basic operations it inherits from NSDictionary . NSMutableDictionary is “toll-free bridged” with its Core Foundation counterpart, CFMutableDictionary .
NSDictionary is a class cluster. This means that the value returned from its init methods is not strictly an NSDictionary, but a subclass that implements the actual functionality. In almost every case, it is better to give your class an NSDictionary as an instance variable or to simply define a category on NSDictionary.
96
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
