My team has decided that new files should be written in swift, and I am seeing an odd problem with using KVC in an Objective-C object to set a property on a Swift object.
My Objective-C sets a property like so: [textObject setValue:0.0 forKey:@"fontSize"]
My Swift object ( textObject
) has a custom setter/getter for this property.
var fontSize: CGFloat? {
get {
return internalTextGraphic?.fontSize
}
set {
internalTextGraphic?.fontSize = newValue
}
}
However, if I set a breakpoint in the set
, it never gets hit.
I have Objective-C objects that also get this same call, and I just implement -setFontSize
, and the execution enters properly.
Why can't I seem to get into my set
method through -setValueForKey
? I have 100% confirmed the textObject
is exists and is the correct type.
EDIT :
Martin R is correct, I had to make the type a non-optional. This is my working code:
var fontSize: CGFloat {
get {
var retFontSize: CGFloat = 0.0
if let fontSize = internalTextGraphic?.fontSize {
retFontSize = fontSize
}
return retFontSize
}
set {
if let textGraphic = internalTextGraphic {
textGraphic.fontSize = newValue
}
}
}
The reason is that a Swift optional struct or enum (in your case CGFloat?
) is not representable in Objective-C (and you won't see that property in the generated "Project-Swift.h"
header file). That becomes more obvious if you mark the property explicitly with @objc
, then you'll get the error message
error: property cannot be marked @objc because its type cannot be represented in Objective-C
If you change the property type to the non-optional CGFloat
then KVC works as expected. It would also work with an optional class type, such as NSNumber?
.
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