断点5.1，同时为文本字段分配常量

Question

我在尝试运行代码时遇到了一个Breakpoint 5.1错误，请记住，这在我的其他应用程序中运行得非常好。

@IBAction func doneTapped(sender: AnyObject) {

    let email = emailField.text


    if (email?.isEmpty != nil) {
        let emailEmpty:UIAlertView = UIAlertView(title: "Please try again", message: "It looks like you forgot to provide us with your email address, try again.", delegate: self, cancelButtonTitle: "Try again")
        emailEmpty.show()
    } else {
        var user = PFUser()

        user.email = email

        user.signUpInBackgroundWithBlock {
            (succeeded: Bool, error: NSError?) -> Void in
            if let error = error {
                let errorString = error.userInfo["error"] as? NSString
                if error.code == 125 {
                    print("Invalid Email Address")
                } else if error.code == 203 {
                    print("Email is already taken")
                }
            } else {
                print("Signup Process Completed.")
            }
        }
    }

}

有人能看出我做错了什么吗？我已经写了大约15次，以确保我没有犯一些愚蠢的错误，但我仍然无法弄清楚为什么它在我运行它时会抛出这个错误。