xcode 不能在 swift 中不同大小的类型之间进行 unsafeBitCast
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can't unsafeBitCast between types of different sizes in swift
提问by Alexander Khitev
when I try to find duplicates in array, I get the error "can't unsafeBitCast between types of different sizes". I find the duplicates following method.
当我尝试在数组中查找重复项时，出现错误“不能在不同大小的类型之间进行 unsafeBitCast”。我发现以下方法重复。
func uniq<S : SequenceType, T : Hashable where S.Generator.Element == T>(source: S) -> [T] {
var buffer = [T]()
var added = Set<T>()
for elem in source {
if !added.contains(elem) {
buffer.append(elem)
added.insert(elem)
}
}
return buffer
}
func filter() {
var arrayForSearch = mp3Files as! [String]
var filteredArray = uniq(arrayForSearch)
println("filtered array \(filteredArray)")
}
The method of find duplicates I knew on this link enter link description here. I use Xcode 6 and Swift 1.2
我在此链接上知道的查找重复项的方法在此处输入链接描述。我使用 Xcode 6 和 Swift 1.2
There is the array in this code.
这段代码中有数组。
var mp3Files: Array<String!>!
func exportData() {
var generalURL: [AnyObject]?
var arrayFiles: Array<NSURL!>!
var directory = fileManager.URLsForDirectory(NSSearchPathDirectory.DocumentDirectory, inDomains: NSSearchPathDomainMask.UserDomainMask)
var urlFromDirectory = directory.first as! NSURL
var file = fileManager.contentsOfDirectoryAtURL(urlFromDirectory, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions.SkipsHiddenFiles, error: nil)!
println("file \(file)")
mp3Files = file.map(){ var array = ["Apple", "Mac", "iPhone", "iPad Air", "Apple", "Air", "Air"]
var filteredArray = Array(Set(array))
println(filteredArray)
.lastPathComponent }.filter(){ var mp3Files: Array<String!>!
.pathExtension == "mp3" }
println("mp3 files \(mp3Files)")
}
When I wrote this code in playground it works. An example
当我在操场上写这段代码时，它可以工作。一个例子
var arrayForSearch = mp3Files as! [String]
How can I use it in my project?
如何在我的项目中使用它？
采纳答案by Rob Napier
import UIKit
class ViewController: UIViewController {
let strArr = ["a","b","a","d","f","f","b"]
override func viewDidLoad() {
super.viewDidLoad()
filter()
}
func uniq<S : SequenceType, T : Hashable where S.Generator.Element == T>(source: S) -> [T] {
var buffer = [T]()
var added = Set<T>()
for elem in source {
if !added.contains(elem) {
buffer.append(elem)
added.insert(elem)
}
}
return buffer
}
func filter() {
var arrayForSearch = strArr
var newArr = uniq(arrayForSearch)
println("filtered array \(newArr)")
}
}
Wow, that's a lot of exclamation points.... They're not needed.
哇，这么多感叹号....它们不是必需的。
filtered array [a, b, d, f]
And the type of mp3Filescan never be the same as [String], so you can't force-cast between them (and would crash if it let you).
并且 的类型mp3Files永远不能与 相同[String]，所以你不能在它们之间强制转换（如果它允许你会崩溃）。
You're using implicitly unwrapped optionals way too often. They are only needed in some special cases. Just change mp3Filesto [String](in which case you won't need the as!at all; you shouldn't need as!very often either).
您经常使用隐式解包的选项。只有在某些特殊情况下才需要它们。只需更改mp3Files为[String]（在这种情况下，您根本不需要as!；您也不应该as!经常需要）。
Similarly, arrayFiles(which you never use), should just be [NSURL], not Array<NSURL!>!.
同样，arrayFiles（您从未使用过），应该只是[NSURL]，而不是Array<NSURL!>!。
回答by Dharmesh Kheni
Here I try same code as you given:
在这里，我尝试与您给出的代码相同的代码：
##代码##And OutPutin console:
而OutPut在控制台：
My be there is a problem when you are casting your array to [String]so check it once again.
当您将数组转换为时，我会遇到问题，[String]因此请再次检查它。
