Error in the "Objective-C Generated Interface Header Name" - ios

Question

I've been upgrading my project to Swift2.
After resolving many errors, i got an error when i build the project.
The error is located in the Objective-V Generated Interface Header,
Xcode is printing this error Type argument 'CGColorRef' (aka 'struct CGColor *') is neither an Objective-C object nor a block type
Here is the code, the error is printed on the line between the **:
SWIFT_CLASS("_TtC519RadialGradientLayer")
#interface RadialGradientLayer : CALayer
**#property (nonatomic, copy) NSArray<CGColorRef> * __nullable colors;**
#property (nonatomic, copy) NSArray<NSNumber *> * __nullable locations;
#property (nonatomic) CGPoint center;
#property (nonatomic) CGFloat startRadius;
#property (nonatomic) CGFloat endRadius;
- (nullable instancetype)initWithCoder:(NSCoder * __nonnull)aDecoder OBJC_DESIGNATED_INITIALIZER;
- (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
- (nonnull instancetype)initWithLayer:(id __nonnull)layer OBJC_DESIGNATED_INITIALIZER;
- (void)drawInContext:(CGContextRef __nonnull)ctx;
+ (BOOL)needsDisplayForKey:(NSString * __nonnull)key;
#end
I guess that is link to this class
class RadialGradientLayer: CALayer {
var colors: [CGColor]? {
didSet {
self.setNeedsDisplay()
}
}
var locations: [CGFloat]? {
didSet {
self.setNeedsDisplay()
}
}
...
}
I didn't found any answer anywhere or even a clue so here i'm.

Answer 1

the error is trying to tell you that you can't have an NSArray contain primitive types.
you would get a similar error if you attempted to do something like this:
#property (nonatomic, strong) NSArray <Int>* intArray;
one way to fix this would be to make your swift class hold an array of UIColor instead of CGColor.