问

Swift字典错误？

mobiledu2502920087 发布于 2023-01-11 19:22

所以我在Swift开始了一个项目,我遇到了这个问题:

这段代码有效:

var dictionary = ["a":"valueOfA","b":"valueOfB","c":"valueOfC"]
println(dictionary)
dictionary["c"] = "newValOfC"
println(dictionary)

这不是:

var dictionary = [:]
dictionary = ["a":"valueOfA","b":"valueOfB","c":"valueOfC"]
println(dictionary)
dictionary["c"] = "newValOfC"
println(dictionary)

给出错误:

Playground execution failed: error: :35:17: error: cannot assign to the result of this expression
dictionary["c"] = "newValC"
~~~~~~~~~~~~~~~ ^

请注意,这不是常量值

那么为什么不行

dictionary = ["a":"valueOfA","b":"valueOfB","c":"valueOfC"]

给出错误？

1 个回答

由于上下文没有提供足够的信息来推断类型,你需要明确地将它命名为字典,否则swift假定它是一个NSDictionary(我不清楚为什么会这样.我假设为了更好的obj-c兼容性) :

以下代码均有效:
```
// Playground
import UIKit

var str:NSString = "Hello, playground"

var d0 = [:]
var d1: Dictionary = [:]

d0.setValue(UIWebView(), forKey: "asdf")

d1["asdf"] = 1
d1["qwer"] = "qwer"
```
2023-01-11 19:23 回答

木子小平方_530

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