func withUnsafePointer<T, Result>(to: inout T, _: (UnsafePointer<T>) throws -> Result) Invokes body with an UnsafePointer to arg and returns the result. Useful for calling Objective-C APIs that take "in/out" parameters (and default-constructible "out" parameters) by pointer. Declaration func withUnsafePointer<T, Result>(to arg: inout T, _ body: (UnsafePointer<T>) throws -> Result) rethrows -> Result