have the compiler add an NSDictionary for every enum type

[headsupftw]

Even though Objective-C is a dynamic language, it's basically impossible to get an enum value given its name as an NSString because an Objective-C/C enum is essentially just an integer (whereas in Java, it can easily be done via the reflection API).

But in the context of protobuf, this problem can be solved by having the compiler add an NSDictionary in which the keys are enum names (NSString) and values are enum values. It could add another dictionary to map enums to their names.

[alexeyxo]

I don't see the meaning...
Can you explain or give an example?

[headsupftw]

Sure, this is an enhancement request BTW.

Below is a snippet from a file generated by protobuf compiler.

typedef NS_ENUM(SInt32, MessageType) {
MessageTypeTimeout = 0,
MessageTypeDisconnect = 1,
MessageTypeCheckin = 2,
};

Now in my source code I already have NSString such as @"Timeout" and @"Disconnect", which I would like to convert to a MessageType enum. I.e. @"Timeout" -> MessageTypeTimeout and @"Disconnect" -> MessageTypeDisconnect.

There's no easy way to do that in Objective-C. But since the enum type was generated by the compiler, it would be nice if the compiler also inserted a NSDictionary in the file. For example,

NSDictionary *messageTypeDict = @{
@"MessageTypeTimeout" : @(MessageTypeTimeout),
@"MessageTypeDisconnect" : @(MessageTypeDisconnect),
@"MessageTypeCheckin" : @(MessageTypeCheckin)
};

It would be even nicer to have the opposite dictionary inserted as well.

NSDictionary *messageTypeStringDict = @{
@(MessageTypeTimeout) : @"MessageTypeTimeout",
@(MessageTypeDisconnect) : @"MessageTypeDisconnect",
@(MessageTypeCheckin) : @"MessageTypeCheckin"
};

The whole point is to provide a way to inspect every enum type, which is something not possible in Objective-C but doable with the help of protobuf compiler.