func (iter *Iterator) ReadObject() (ret string) {
	c := iter.nextToken()
	switch c {
	case 'n':
		iter.skipThreeBytes('u', 'l', 'l')
		return ""  
	case '{':
		c = iter.nextToken()
		if c == '"' {
			iter.unreadByte()
			return string(iter.readObjectFieldAsBytes())
		}
		if c == '}' {
			return ""  
		}
		iter.ReportError("ReadObject", `expect " after {`)
		return
	case ',':
		return string(iter.readObjectFieldAsBytes())
	case '}':
		return "" // end of object
	default:
		iter.ReportError("ReadObject", fmt.Sprintf(`expect { or , or } or n, but found %s`, string([]byte{c})))
		return
	}
}
ReadObject read one field from object.
If object ended, returns empty string.
Otherwise, returns the field name.
package jsoniter
import (
	"fmt"
	"unicode"
	"unsafe"
)