問題在我的ViewController訪問功能的斯威夫特字典變量中

Question

類

初始化我的ViewController類，像這樣：

class ViewController: UIViewController { 

    required init(coder aDecoder: NSCoder) { 
     super.init(coder: aDecoder) 

     // Create a dict of images for use with the UIView menu tab 
     var imageDict = [String:UIImage]() 
     imageDict["hudson_terrace"] = UIImage(named: "hudson_terrace") 
     imageDict["sky_room"] = UIImage(named: "sky_room") 
     imageDict["rivington"] = UIImage(named: "rivington") 
     imageDict["highline_ballroom"] = UIImage(named: "highline_ballroom") 
     imageDict["gansevoort_park_redroom"] = UIImage(named: "gansevoort_park_redroom") 
     imageDict["gansevoort_park_rooftop"] = UIImage(named: "gansevoort_park_rooftop") 
     imageDict["evr"] = UIImage(named: "evr") 

    } 

在課堂後來寫到這功能...

func addImageViews() { 

     // loop through imageDict and add all the images as UIView subviews of menuScrollView 
     for (venue_name, image) in self.imageDict { 

     } 
    } 

和我收到錯誤「ViewController」沒有名爲「imageDict」的成員。

不知道爲什麼imageDict在函數內部不可用。任何人都可以提出一個更好的地方來放置字典和如何訪問它？

Answer 1

您聲明imageDict作爲init初始值設定程序的本地變量，因此它僅存在於該上下文中。只要函數（初始化程序）退出，變量就會被釋放，並且不能在該上下文之外被引用。

爲了從類的任何方法引用它，你應該把它聲明爲類的屬性：

class ViewController: UIViewController { 
    var imageDict = [String:UIImage]() 

    required init(coder aDecoder: NSCoder) { 
     super.init(coder: aDecoder) 

     // Create a dict of images for use with the UIView menu tab 
     imageDict["hudson_terrace"] = UIImage(named: "hudson_terrace") 
     imageDict["sky_room"] = UIImage(named: "sky_room") 
     imageDict["rivington"] = UIImage(named: "rivington") 
     imageDict["highline_ballroom"] = UIImage(named: "highline_ballroom") 
     imageDict["gansevoort_park_redroom"] = UIImage(named: "gansevoort_park_redroom") 
     imageDict["gansevoort_park_rooftop"] = UIImage(named: "gansevoort_park_rooftop") 
     imageDict["evr"] = UIImage(named: "evr") 
    } 

通過這樣做，屬性是提供給任何類的實例方法。