"Bad property protocol declaration" when trying to initialize model class which is in framework

Question

I have been stretching my head from two days to solve this issue.

I have created iOS universal framework which contains my model classes derived from JSONModel. For example,

@protocol XYZ
@end

@interface XYZ : JSONModel
@property(nonatomic,strong) NSString * name;
@end

Now, whenever I use this "Framework" in other project and try to initialize "XYZ" model class with dictionary,

NSError* err = nil;
XYZ * xyz = [[XYZ alloc] initWithDictionary:jsonDictionary error:&err];

it crashes saying "Bad property protocol declaration".

It is working fine if I do not use framework and put those model class directly in my project. Don't know why such a wired behavior.

I have been looking badly for solution from two days and lots of waste of time. I can see this issue is also raised in github but no any answer from developers. It is very frustrating and even I can't drop JSONModel at this very mature stage of my project. I am having so many model classes and very complex structures that I cannot switch to another library.

Please. Any help would be greatly appreciated. Thank you in advance.

Rakesh Pethani · Accepted Answer · 2015-09-14T10:04:22.280

It seems that model classes that was in framework was not loaded by runtime before it was being initialized with dictionary because it was in framework, that's why in following code

//few built-in transformations
-(id)__transform:(id)value forProperty:(JSONModelClassProperty*)property error:(NSError**)err
{
    Class protocolClass = NSClassFromString(property.protocol);
    if (!protocolClass) {

        //no other protocols on arrays and dictionaries
        //except JSONModel classes
        if ([value isKindOfClass:[NSArray class]]) {
            @throw [NSException exceptionWithName:@"Bad property protocol declaration"
                                       reason:[NSString stringWithFormat:@"<%@> is not allowed JSONModel property protocol, and not a JSONModel class.", property.protocol]
                                     userInfo:nil];
        }
        return value;
    }

    ...........
}

"protocolClass" was Nil and the error was being thrown.

Solution was to simply add "-Objc" flag in Other linkers flag, so that classes can be loaded by runtime from static library before they get used.

Hope this helps to others also.

"Bad property protocol declaration" when trying to initialize model class which is in framework

1 Answers1