New Objective C syntax (lightweight generics)

[pjebs]

In the new version of Objective C (on XCode 7), we can now specify what a NSArray can contain.

Will your library support this? It will definitely reduce the amount of casting we need to do.

Say we have a JSONModel subclass called Cars.

Say we have another JSONModel subclass called Person:

@Property (strong, nonatomic) NSArray < Cars * > * cars; //Restricting NSArray to Cars

rather than currently:

@protocol Cars
@EnD

@Property (strong, nonatomic) NSArray < Cars > * cars; //Currently

[vaddieg]

W/ Xcode 7 you have to forward-declare protocol name explicitly to suppress compiler error

[MellongLau]

Hope @pjebs opinion can be accepted.

[MellongLau]

Find the answer : http://stackoverflow.com/questions/30866197/how-can-i-find-out-the-objective-c-generics-type

The lightweight generics introduced in Xcode 7 are just compile time hints to help the compiler raise warnings, but at run time you get the same old behavior with your variable being just NSArrays of ids.

So, I think it is not possible to do some thing like that.

[ghost]

Workaround:

@interface Model: JSONModel
@property (strong, nonatomic) NSArray < Cars * > * cars;
@end

@implementation Model
- (void)setCars:(NSArray<NSDictionary*> *)cars {
    NSMutableArray* mutArray = [NSMutableArray array];

    for (NSDictionary* carDict in cars) {
        NSError* error;
        Cars* car = [[Cars alloc] initWithDictionary:carDict error:&error];

        if (car && !error) {
            [mutArray addObject:car];
        }
    }

    _cars = [NSArray arrayWithArray:mutArray];
}
@end

Unfortunly you need to do this with every array.

[jkmathew]

I also tried this by adding new type annotation(with generics) with arrays, but its not giving any information about the added annotation/generics in runtime.
That is while fetching property attributes with property_getAttributes() its not giving any information about the annotation.

@icanzilb , @dbachrach do you have any thoughts about this?

[dbachrach]

Yeah, the objc generics implementation does not persist data at runtime, so it's not usable to JSONModel.

[skerkewitz]

Looks to me like it is even worse:

If you do:

@protocol Cars
@end
@property (strong, nonatomic) NSArray <Cars> *cars; // JSONModel way

then Swift will map cars to [AnyObject] as Swift does not know the type.

If you do:

@property (strong, nonatomic) NSArray <Cars *> *cars; 

Then swift will map it to [Cars] but JSONModel will not parse the json correctly as it does not know the type. So it seems like you can't have both.

[pjebs]

I turns out you can have both (I think).
<cars *, cars>

[MellongLau]

@pjebs, you can not do that, it will cause compile error.

[vaddieg]

Fortunatelly, you can use C macro w/ setCars: workaround
#define JSON_SETTER(className, propName)

[pjebs]

@vaddieg can you elaborate and give more details of usage?

[vaddieg]

Very draft marco, w/o error checking

#import "JSONModel.h"

#define JSONSetterImp(setterSignarure, ClassName, ivarName) \
- (void) setterSignarure :(NSArray<NSDictionary*> *)array {\
    NSMutableArray *ma = [NSMutableArray arrayWithCapacity:array.count];\
    for (NSDictionary* object in array) { \
        ClassName *model = [[ClassName alloc] initWithDictionary:object error:NULL]; \
        if (model) { \
            [ma addObject:model]; \
        } \
    } \
    ivarName = [ma copy];\
}

@interface Car : JSONModel
@end

@interface Parking : JSONModel
@property (strong, nonatomic) NSArray<Car*> *cars;

@end

And Implementation of setter will look like:

@implementation Parking

JSONSetterImp(setCars, Car, _cars)

@end

[pjebs]

I have verified that you can do this:
<cars *><cars>

[MellongLau]

@pjebs GOOD JOB.

[vaddieg]

@pjebs Nice. Case is closed I think

[vaddieg]

@icanzilb pls update Readme.md Model Collection example