如何Optional("")在显示时删除可选值上的文本而不必强制输入!。
Optional("")
!
更新资料
// I have somthing like this declared outside class // I put question mark wrapper since I don't know when this session might have a value var url = "\(self.session?.apiURL)/api/products.json" // private session private var _session:Session? class MyClass { . . . // the value of apiURL depends on session, session has optional value and declared as // custom lazy loaded var session var session:Session? { get { if _session == nil { _session = // fetch from coredata store if there is an active session. Might return nil // if no active session if _session == nil { // I just print "No active session" } } // return _session may or may not contain any value return _session } } }
当会话具有值时,其url具有值:
url
Optional("my_api_url_here")/api/products.json
您可以使用??(null合并运算符)解开它,并提供默认值(如果为nil)
??
let sessionApiURL = self.session?.apiURL ?? "" var url = "\(sessionApiURL)/api/products.json"