func write(t Format, buf []byte) (<-chan struct{}, error) {
	done := make(chan struct{}, 1)
	switch t {
	case FmtText:
		cs := C.CString(string(buf))
		defer C.free(unsafe.Pointer(cs))
		C.clipboard_write_string(cs)
		return done, nil
	case FmtImage:
		return nil, errors.New("unimplemented")
	default:
		return nil, errors.New("unimplemented")
	}
}
SetContent sets the clipboard content for iOS
package clipboard
import "C"
import (
	"bytes"
	"context"
	"errors"
	"time"
	"unsafe"
)
func read(t Format) (buf []byte, err error) {
	switch t {
	case FmtText:
		return []byte(C.GoString(C.clipboard_read_string())), nil
	case FmtImage:
		return nil, errors.New("unimplemented")
	default:
		return nil, errors.New("unimplemented")
	}
}