pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified)

[AlexPan1992]

Hi,

When using the SDK in Xcode, there are many warnings like:

pointer is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified)

It would be great if the headers could be updated with proper nullability specifiers (e.g. _Nonnull / _Nullable) or wrapped with NS_ASSUME_NONNULL_BEGIN/END. This will remove warnings and improve Swift interoperability.

Thanks!