数组元素无法桥接到 Objective-C [英] Array element cannot be bridged to Objective-C

问题描述

我有这段代码可以创建一个视图并对其应用渐变.

I have this code that creates a view and applies a gradient to it.

import UIKit
import QuartzCore


let rect : CGRect = CGRectMake(0,0,320,100)

var vista : UIView = UIView(frame: rect)

let gradient : CAGradientLayer = CAGradientLayer()
gradient.frame = vista.bounds

let cor1 = UIColor.blackColor()
let cor2 = UIColor.whiteColor()

let arrayColors = [cor1.CGColor, cor2.CGColor]

gradient.colors = arrayColors

view.layer.insertSublayer(gradient, atIndex:0)

Xcode 没有给我任何编译错误，但是代码在线上崩溃了

Xcode is giving me no compile error, but the code is crashing on the line

let arrayColors = [cor1.CGColor, cor2.CGColor]

带有消息数组元素无法桥接到Objective-C

事实上，我原以为它会在那里崩溃，因为我不确定如何在 Swift 上创建一组 CGColors.令人惊讶的是 Xcode 提到了 Objective-C.在我看来，我正在迅速创建一个 CGColorRef...

In fact I was expecting it to crash there, because I am not sure how I can create an array of CGColors on Swift. The surprise here is Xcode mentioning Objective-C. In my mind I was creating a CGColorRef in swift...

有什么线索吗?为什么要提到 Objective-C，我该如何解决?

Any clues? Why is it mentioning Objective-C and how do I solve this?

推荐答案

之所以提到 Objective-C，是因为 UIKit 和 QuartzCore 是 Objective-C 框架.特别是，gradient.colors = arrayColors 正在调用一个需要 NSArray 的 Objective-C 方法.

The reason Objective-C is mentioned is because UIKit and QuartzCore are Objective-C frameworks. In particular, gradient.colors = arrayColors is calling an Objective-C method that expects an NSArray.

这似乎是一个错误，因为 Apple 的文档听起来像是数组应该自动桥接到 NSArray，只要数组中的项目可以被视为 AnyObject:

This seems like a bug, as Apple's documentation makes it sound like that the array should auto-bridge to an NSArray so long as the items in the array can be considered AnyObject:

当你从一个 Swift 数组桥接到一个 NSArray 对象时，元素在 Swift 数组中必须与 AnyObject 兼容.例如，一个 SwiftInt[] 类型的数组包含 Int 结构元素.Int 类型是不是类的实例，而是因为 Int 类型桥接到NSNumber 类，Int 类型与 AnyObject 兼容.因此，你可以将 Int[] 类型的 Swift 数组桥接到 NSArray 对象.如果Swift 数组中的元素与 AnyObject 不兼容，这是一个运行时错误当您桥接到 NSArray 对象时发生.

When you bridge from a Swift array to an NSArray object, the elements in the Swift array must be AnyObject compatible. For example, a Swift array of type Int[] contains Int structure elements. The Int type is not an instance of a class, but because the Int type bridges to the NSNumber class, the Int type is AnyObject compatible. Therefore, you can bridge a Swift array of type Int[] to an NSArray object. If an element in a Swift array is not AnyObject compatible, a runtime error occurs when you bridge to an NSArray object.

您也可以按照上述相同的桥接规则，直接从 Swift 数组字面量创建 NSArray 对象.当你显式键入一个常量或变量作为 NSArray 对象并赋值它是一个数组文字，Swift 创建一个 NSArray 对象而不是一个Swift 数组.

You can also create an NSArray object directly from a Swift array literal, following the same bridging rules outlined above. When you explicitly type a constant or variable as an NSArray object and assign it an array literal, Swift creates an NSArray object instead of a Swift array.

目前，解决方法是将 arrayColors 声明为 NSArray:

For now, a work around would be either to declare arrayColors as an NSArray:

let arrayColors: NSArray = [cor1.CGColor, cor2.CGColor]

或者将其声明为采用 AnyObject:

Or to declare it as taking AnyObject:

let arrayColors: Array = [cor1.CGColor, cor2.CGColor]

这篇关于数组元素无法桥接到 Objective-C的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！