Access NSLog through Cgo for iOS NetworkExtension logging

src/yggdrasil/mobile_ios.go

@@ -0,0 +1,25 @@
+// +build mobile,darwin
+
+package yggdrasil
+
+/*
+#cgo CFLAGS: -x objective-c
+#cgo LDFLAGS: -framework Foundation
+#import <Foundation/Foundation.h>
+void Log(const char *text) {
+  NSString *nss = [NSString stringWithUTF8String:text];
+  NSLog(@"%@", nss);
+}
+*/
+import "C"
+import "unsafe"
+
+type MobileLogger struct {
+}
+
+func (nsl MobileLogger) Write(p []byte) (n int, err error) {
+	p = append(p, 0)
+	cstr := (*C.char)(unsafe.Pointer(&p[0]))
+	C.Log(cstr)
+	return len(p), nil
+}