参考官方文档:
Migrating to Unified API for Components
#if __UNIFIED__ ... // Mappings Unified CoreGraphic classes to MonoTouch classes using RectangleF = global::CoreGraphics.CGRect; using SizeF = global::CoreGraphics.CGSize; using PointF = global::CoreGraphics.CGPoint; #else ... // Mappings Unified types to MonoTouch types using nfloat = global::System.Single; using nint = global::System.Int32; using nuint = global::System.UInt32; #endif