由于未捕获的异常“NSRangeException”而终止应用程序，原因：“*** -[__NSArray0 objectAtIndex:]: index 0 beyond bounds for empty NSArray”

Question

我正在通过 API 获取标签、文本和图像。当 API 有数据时，它显示没有错误。但是当 API 为 nil 时，它会抛出错误：

由于未捕获的异常“NSRangeException”而终止应用程序，原因： '*** -[__NSArray0 objectAtIndex:]: 索引 0 超出范围为空 NSArray'。

如果 API 提供 nil 值但防止崩溃，我需要它显示 null。任何人都请帮助在 Swift 3 中解决这个问题。代码如下：

import UIKit
import Alamofire

class Instructors: UIViewController {

    @IBOutlet var fullName: UILabel!
    @IBOutlet var post: UILabel!
    @IBOutlet var descriptionName: UITextView!
    @IBOutlet var instructorImage: UIImageView!

    var dictDataContent:NSDictionary = NSDictionary()
    var dictData:NSArray = NSArray()
    var dictprofile:NSDictionary = NSDictionary()

    override func viewDidLoad() {
        super.viewDidLoad()
        self.dictData = (dictDataContent.value(forKey: "instructors") as AnyObject) as! NSArray
        self.dictprofile = (dictData.object(at: 0) as AnyObject) as! NSDictionary
        let url:URL = URL(string: (self.dictprofile.value(forKey: "profile_image")) as! String)!
        SDWebImageManager.shared().downloadImage(with: url, options: [],progress: nil, completed: {[weak self] (image, error, cached, finished, url) in
            if self != nil {
              self?.instructorImage.image = image
            }
        })

        self.fullName.text = dictprofile.value(forKey: "full_name") as! String?
        self.post.text = dictprofile.value(forKey: "designation") as! String?
        self.descriptionName.text = dictprofile.value(forKey: "description") as! String?
    }

}

Answer 1

所以我从您的问题中了解到您的 API 可能有数据，有时没有数据。这是Optionals 在swift 中的行为。所以你需要有optional 变量来存储你的数据。

将您的 NSDictionary 和 NSArray 变量更改为 optional 可能会有所帮助。试试下面的代码：

class Instructors: UIViewController {
    @IBOutlet var fullName: UILabel!
    @IBOutlet var post: UILabel!
    @IBOutlet var descriptionName: UITextView!
    @IBOutlet var instructorImage: UIImageView!

    var dictDataContent:NSDictionary?
    var dictData:NSArray?
    var dictprofile:NSDictionary?
    override func viewDidLoad() {
        super.viewDidLoad()
        dictData = dictDataContent?.value(forKey: "instructors") as? NSArray
        if let count = dictData?.count, count > 0 {
            dictprofile = dictData?.object(at: 0) as? NSDictionary
        }
        if let urlString = dictprofile?.value(forKey: "profile_image") as? String {
            if let url = URL(string: urlString) {
                SDWebImageManager.shared().downloadImage(with: url, options: [],progress: nil, completed: {[weak self] (image, error, cached, finished, url) in
                    if self != nil {
                        self?.instructorImage.image = image
                    }
                })
            }
        }
        fullName.text = dictprofile?.value(forKey: "full_name") as? String
        post.text = dictprofile?.value(forKey: "designation") as? String
        descriptionName.text = dictprofile?.value(forKey: "description") as? String
    }
}