ios - UILabel 中字母的 Swift : How do I find the position(x, y)？

Question

我试图找到一个字母在 labelText 中的位置。Objective C 中的代码是

NSRange range = [@"Good,Morning" rangeOfString:@","];
NSString *prefix = [@"Good,Morning" substringToIndex:range.location];
CGSize size = [prefix sizeWithFont:[UIFont systemFontOfSize:18]];
CGPoint p = CGPointMake(size.width, 0);
NSLog(@"p.x: %f",p.x);
NSLog(@"p.y: %f",p.y);

请有人告诉我我们如何在 swift 中编写上面的代码？我发现计算字符串的范围有点困难。

Answer 1

我最终会推荐以下变体:

extension String {

    func characterPosition(character: Character, withFont: UIFont = UIFont.systemFontOfSize(18.0)) -> CGPoint? {

        guard let range = self.rangeOfString(String(character)) else {
            print("\(character) is missed")
            return nil
        }

        let prefix = self.substringToIndex(range.startIndex) as NSString
        let size = prefix.sizeWithAttributes([NSFontAttributeName: withFont])

        return CGPointMake(size.width, 0)
    }
}

客户代码:

let str = "Good,Morning"
let p = str.characterPosition(",")