如何加载Swift Bundle中指定文件夹内的资源文件

需求说明 #

需要加载default-sound目录下的文件a，该文件在Bundle中的结构如下：
#

实现方式1：路径拼接定位 #

首先参照普通目录结构的使用方式，尝试用/拼接路径定位文件夹，实现代码如下：

import Foundation
import AVFoundation

struct TtsPronounciationError: Error {
    enum ErrorKind {
        case loadingError
    }
    
    let kind: ErrorKind
    let path: String
    let char: Character
    
    init(kind: ErrorKind, path: String, char: Character) {
        self.path = path
        self.kind = kind
        self.char = char
    }
}

struct TtsPronounciation {
    var char: Character
    var audioFile: AVAudioPlayer
    
    static func fromBundle(char: Character, bundleFileName: String) throws -> TtsPronounciation {
        Bundle.main.load()
        
        if let path = Bundle.main.path(forResource: bundleFileName, ofType: nil) {
            let url = URL(fileURLWithPath: path)
            do {
                let sound = try AVAudioPlayer(contentsOf: url)
                return self.init(char: char, audioFile: sound)
            } catch let e {
                print(#function, "error", e)
                throw TtsPronounciationError(kind: .loadingError, path: bundleFileName, char: char)
            }
        } else {
            print(#function, " - error", "could not find \(bundleFileName)")
            throw TtsPronounciationError(kind: .loadingError, path: bundleFileName, char: char)
        }
    }
}

do {
    var a = try TtsPronounciation.fromBundle(char: "a", bundleFileName: "default-sound/a")
}
catch {
    print("could not find the file in bundle")
}

实现方式2：inDirectory参数定位 #

之后尝试使用Bundle.main.path方法的inDirectory参数定位Bundle目录中存储的文件，实现代码如下：

import Foundation
import AVFoundation

struct TtsPronounciationError: Error {
    enum ErrorKind {
        case loadingError
    }
    
    let kind: ErrorKind
    let path: String
    let char: Character
    
    init(kind: ErrorKind, path: String, char: Character) {
        self.path = path
        self.kind = kind
        self.char = char
    }
}

struct TtsPronounciation {
    var char: Character
    var audioFile: AVAudioPlayer
    
    static func fromBundle(char: Character, bundleFileName: String, inDirectory: String?) throws -> TtsPronounciation {
        Bundle.main.load()
        
        if let path = inDirectory != nil ? Bundle.main.path(forResource: bundleFileName, ofType: nil, inDirectory: inDirectory) : Bundle.main.path(forResource: bundleFileName, ofType: nil) {
            let url = URL(fileURLWithPath: path)
            do {
                let sound = try AVAudioPlayer(contentsOf: url)
                return self.init(char: char, audioFile: sound)
            } catch let e {
                print(#function, "error", e)
                throw TtsPronounciationError(kind: .loadingError, path: bundleFileName, char: char)
            }
        } else {
            print(#function, " - error", "could not find \(bundleFileName)")
            throw TtsPronounciationError(kind: .loadingError, path: bundleFileName, char: char)
        }
    }
}

do {
   var a = try TtsPronounciation.fromBundle(char: "a", bundleFileName: "a", inDirectory: "default-sound")
}
catch {
    print("could not locate the sound")
}

内容的提问来源于stack exchange，提问作者The epic face 007