我有一个类型结构课程
struct Course {
let title: String
let subtitle: String
let instructor: String
let color: String
init(title: String, subtitle: String, instructor: String, color: String) {
self.title = title
self.subtitle = subtitle
self.instructor = instructor
self.color = color
}
}
这是我的代码,试图将结构课程类型的数据附加到课程中,但最终得到零错误。我该怎么办?
var courses: [Course]!
courses?.append(Course(title: "Team-Based Mobile Device Application Development", subtitle: "2018SP INFOTC 4500/JOURN 4444 Moore & Musser", instructor: "", color: ""))
您需要初始化数组。到目前为止,您所做的只是声明它。
改变:
var courses: [Course]!
自:
var courses = [Course]()
这会将courses
声明并初始化为空的Course
数组。
然后:
courses?.append(Course...
成为:
courses.append(Course...
您需要在使用变量之前对其进行初始化。所以需要改变
var courses: [Course]!
courses?.append(Course(title: ...
自
var courses: [Course] = []
courses.append(Course(title: ...
最好的方法是
var courses: [Course]! = []
带追加功能
courses.append(Course(title: "Team-Based Mobile Device Application Development", subtitle: "2018SP INFOTC 4500/JOURN 4444 Moore & Musser", instructor: "", color: ""))