import UIKit
var inputField = UITextField()
inputField.text?.isEmpty // true !!!
// by deafault it is empty, so i set it
inputField.text = "default text"
let defaultText = "PLACEHOLDER"
let newText = inputField.text?.isEmpty == true ? defaultText : inputField.text!
let newText2 = inputField.text ?? defaultText
print(newText) // default text
print(newText2) // default text
程式码中newText2
为空字符串,因为inputField.text不是零
的安全方法如何做到这一点(inputField.text可能是零,空或一些文本)
import UIKit
var inputField = UITextField()
let defaultText = "PLACEHOLDER"
if let txt = inputField.text {
inputField.text = txt.isEmpty ? defaultText : txt
}
let newText = inputField.text ?? defaultText
print(inputField.text, newText) // Optional("PLACEHOLDER") PLACEHOLDER
因此,如果inputField.text为空或零,则设置为某个默认值,否则文本不会更改
“text”属性的值是否为“nil”?我认为这将是不一样的空串。 –