Swift报错：“Return from initializer without initializing all stored properties”

struct User {
    var email: String
    var firstName: String
    var lastName: String
    init() {
    }
}

解决方案：

给成员变量添加?修饰符使其变成Optional类型，或者赋初始值，或者在init()中进行赋值

struct User {
    var email: String?
    var firstName: String?
    var lastName: String?
    init() {
    }
}

struct User {
    var email: String = ""
    var firstName: String = ""
    var lastName: String = ""
    init() {
    }
}

struct User {
    var email: String
    var firstName: String
    var lastName: String
    init() {
        email = ""
        firstName = ""
        lastName = ""
    }
}