Swift compile error, subclassing NSValue, using super.init(nonretainedObject:) -

this code

class id<t: anyobject> : nsvalue {     init(baseobject: t) {         super.init(nonretainedobject: baseobject)     } } 

gives compiler error:

error: must call designated initializer of superclass 'nsvalue'     super.init(nonretainedobject: baseobject)     ^ 

how rid of this?

things thought of

i thought error might because nsvalue initializer has anyobject? type (note well: postfix ?). tried various flavors of casting , [?!] postfixing in places, , fixed nothing.

also, presumably nsvalue(nonretainedobject:) must call designated initializer, right?

nsvalue(nonretainedobject:) isn't designated initializer. initializer listed in nsvalue reference (and hence designated initializer) nsvalue(value:cconstvoidpointer, withobjctype type:cstring)

the other constructors convenience constructors derived class helper methods.

you might try:

init(baseobject: t) {     super.init(bytes:&baseobject, withobjctype:"^v") } 

"^v" type string returned nsvalue created valuewithnonretained....

unfortunately, i'm not coming appropriate way pass baseobject cconstvoidpointer.

barring that, best thing can come wrap nsvalue instead of subclassing it:

class id<t:anyobject> {     let wrapped:nsvalue      init(baseobject:t) {         wrapped = nsvalue(nonretainedobject:baseobject)     } } 

finally got work, it's little bit ugly, add convenience constructor wraps nonretainedobject constructor , use in subclass:

extension nsvalue {     convenience init<t:anyobject>(unretained:t) {         self.init(nonretainedobject:unretained)     } }   class id<t>:nsvalue {     convenience init<t:anyobject>(unretained:t) {         self.init(unretained:unretained)     } } 

depending on you're trying category alone might sufficient?