Swift将字符转换为字符串 [英] Swift Converting Character to String

问题描述

我将字符类型转换为字符串类型时遇到问题。首先，我在String的下面扩展，用于在String中查找第n个字符。

I have an issue with converting character type to String type. First of all, I have below extension of String for finding nth character within String.

extension String {
    func characterAtIndex(index: Int) -> Character? {
        var cur = 0
        for char in self {
            if cur == index {
                return char
            }
            cur++
        }
        return nil
    }
}

我得到了我想要的东西这个类扩展。但是，当我将第n个字符用于我的自定义UIButton的标题时，会出错。我的Uibutton类是

I get what I want with this class extension. However when I use that nth character for title of my custom UIButton, gives an error. My Uibutton Class is

class hareketliHarfler: UIButton {
    init(frame: CGRect) {
        super.init(frame: frame)
        // Initialization code
    }
    func getLetter(letter:String!){
        self.titleLabel.text = letter 
    }
}

当我尝试访问getLetter（letter：String）函数时显示错误。以下是主视图控制器代码的示例：

The error show when i try to access "getLetter(letter:String)" function. Here is example of main view Controller codes:

    var harfim = hareketliHarfler(frame: CGRectMake(100,100,100,100))
var str="This is my String"
var bufi=str.characterAtIndex(3)
    harfim.getLetter(bufi as AnyObject) ****

在 * 部分我尝试.getLetter（bufi）,. getLetter（bufi as String）我也尝试更改参数类型的函数。看起来像：func getLetter（letter：Character！）或func getLetter（letter：AnyObject！）... etc
没找到方法。需要帮助。谢谢

In * section I try .getLetter(bufi), .getLetter(bufi as String) also I try to change parameter type of function. Look like: func getLetter(letter:Character!) or func getLetter(letter:AnyObject!)...etc Didn't find a way. Need a help on that. Thank you

推荐答案

你的问题非常简单：你的characterAtIndex函数返回一个Character，self.titleLabel.text是一个String。你无法隐式地在两者之间进行转换。最简单的方法是使用String初始化器将Character转换为String：

Your problem is quite simple: your characterAtIndex function returns a Character, and self.titleLabel.text is a String. You can't convert between the two implicitly. The easiest way would be to turn the Character into a String using the String initialiser:

// ch will be Character? type.
if let ch = str.characterAtIndex(3) {
    // Initialise a new String containing the single character 'ch'
    harfim.getLetter(String(ch))
} else {
    // str didn't have a third character.
}

与其他解决方案不同，这对于不寻常的Unicode字符是安全的，并且不会初始化一个可能很大的数组或迭代整个String只是为了得到第三个字符。

Unlike other solutions, this is safe for unusual Unicode characters, and won't initialise a potentially large array or iterate the whole String just to get the third character.

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