如何使用UnsafeMutablePointer在Swift拥有一些核心基础框架？为什么有一个UnsafeMutablePointer?给出，一般：有些UnsafeMutablePointer在哪里typealiasSomeType=OpaquePointer具体示例API//SOURCE:importApplicationServices.PrintCoretypealiasPMPrinter=OpaquePointerfuncPMSessionGetCurrentPrinter(_printSession:PMPrintSession,_currentPrinter:UnsafeMutab