"串?' 不能转换为'NSString'"(Xcode 7迁移后)

Nie*_*ved 4 ios swift ios9

你好我正在开发项目(在objective-c中完成它)但是一个类在Swift中被写了.迁移到XCODE 7 for ios9编译器后回到我的错误:'String?' 代码不能转换为'NSString':

if let view = self.emailTextField.rightView {
                    if (self.emailTextField.text as NSString).validateEmail() {
                        self.emailTextField.rightView?.alpha = 1
                    } else {
                        self.emailTextField.rightView?.alpha = 0
                    }
                }
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来自Swift2老板:)的任何建议?

Vat*_*not 9

老板建议:

self.emailTextField.text as NSStringself.emailTextField.text! as NSString

:)