斯威夫特的Xcode錯誤「無法下標類型‘[ListOfAnimals]’的值

Question

下面是類的截圖，我得到了錯誤：

http://i.stack.imgur.com/MOmlM.png

我不知道到底是什麼標手段即使在起初我以爲這意味着它是一個類的現有成員。

這裏是一流的

import UIKit 
class AnimalListTableViewController: UITableViewController 
{ 
    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
     return 4 
    } 

    override func prepareForSegue(segue: UIStoryboardSegue, 
     sender: AnyObject?) 
    { 
     if let detailViewController = segue.destinationViewController as? DetailViewController, let indexPath = self.tableView.indexPathForSelectedRow { 
      detailViewController.animal = animals[indexPath.row] //This is where I get the error: Cannot subscript a value of type '[ListOfAnimals]' 
     } 
    } 
} 

這裏是ListOfAnimals類

import UIKit 


let animals = [ 
    ListOfAnimals(name: "Cow", 
     shortDescription: "Cattle", 
     longDescription: "A cow is a mature female and bull of an adult male of a bovine family. A heifer is a female cow that hasn't had a calf yet. Cattle is the name for the whole cow family. THere are about 920 different breeds of cows in the world."), 

    ListOfAnimals(name: "Bird", 
     shortDescription: "Usually small, has wings, feathers, and can fly.", 
     longDescription: "A warm-blooded egg-laying vertebrate distinguished by the possession of feathers, wings, and a beak and (typically) by being able to fly."), 

    ListOfAnimals(name: "Dolphin", 
     shortDescription: "A large fish", 
     longDescription: "A small gregarious toothed whale that typically has a beaklike snout and a curved fin on the back. Dolphins have become well known for their sociable nature and high intelligence."), 

    ListOfAnimals(name: "Dog", 
     shortDescription: "Man's best friend", 
     longDescription: "A domesticated carnivorous mammal that typically has a long snout, an acute sense of smell, and a barking, howling, or whining voice. It is widely kept as a pet or for work or field sports."), 

    ListOfAnimals(name: "Zebra", 
     shortDescription: "A horse with white and black stripes", 
     longDescription: "an African wild horse with black-and-white stripes and an erect mane."), 

] 

class ListOfAnimals 
{ 


    var name: String 
    //var type: Type 
    var shortDescription: String 
    var longDescription: String 

    init(name: String, shortDescription: String, longDescription: String) 
    { 
     self.name = name 
     self.shortDescription = shortDescription 
     self.longDescription = longDescription 
    } 

} 

這裏是動物類

import UIKit 

class Animal 
{ 
    var animal = Animal.self 
    var name: String 


    var shortDescription: String 
    var longDescription: String 
    init(name: String, shortDescription: String, longDescription: String) { 
     self.name = name 
     self.shortDescription = shortDescription 
     self.longDescription = longDescription 

    } 

} 

編輯：當我使用「動物[indexPath.row]？‘我得到這個錯誤：’對非可選值不能使用可選的鏈接鍵入'[ListOfAnimals]'「.....但是當我使用」動物！[indexPath.row]「時，我得到這個錯誤：」無法強制展開非可選類型的值[ListOfAnimals]'「.. ...但後來當我使用「動物[indexPath.row]」，我得到這個錯誤：「不能下標值類型'[ListOfAnimals]'」.....但後來我使用該行「var animal = Animal.self「，因爲我是偏執的，如果我沒有使用它，comp iler只是抱怨，並說動物沒有初始化或類似的東西

Answer 1

編輯：與您最新的代碼更改，Animal應該是animals。 Animal是該類的名稱，而您正在嘗試索引其中一個動物。

是否animals只聲明一次？錯誤消息表明，在您的第一課中，animals是可選的，在這種情況下，您將不得不用後綴'？'要麼 '！'。但是，您的ListOfAnimals類顯示它是非可選的，如果這是相同的參考。

// If animals is non-Optional... 
let animal = animals[indexPath.row] 

// If animals is Optional 
let animal = animals?[indexPath.row] 

// If animals is Optional, but you know it's non-nil 
let animal = animals![indexPath.row] 

儘管如此，總的來說，目前還不清楚爲什麼ListOfAnimals存在。它看起來像你想從動物數組中獲得AnimalListTableViewController中的一個動物。因此，我希望：

，也是你的numberOfRowsInSection返回animals.count。因此上述let將在AnimalListTableViewController中，因此ListOfAnimals不需要存在。

這一點也不清楚爲什麼你需要下面一行：

var animal = Animal.self