Use of unresolved identifier 'boundingRect'

Question

I have very weird problem with below code.

extension String {
        func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
            let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
            let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font: font], context: nil)

            return ceil(boundingBox.height)
        }
}

It always throwing below compiler error.

But if I use self.boundingRect then it compile successfully and run the application but after launched app on simulator it automatically revert to again boundingRect (Removing self).

So everytime I need to add self. to execute app.

Even I'm doing this, but every-time it revert as I explained in question. Anyway I already got root cause of this problem through Prashant's answer. — Sunil Targe, Jul 30 '18 at 09:17

score 6 · Accepted Answer · edited Jun 20 '20 at 09:12

6

It is because the boundingRect is NSString's extension method

extension NSString {

    @available(iOS 7.0, *)
    open func draw(with rect: CGRect, options: NSStringDrawingOptions = [], attributes: [NSAttributedStringKey : Any]? = nil, context: NSStringDrawingContext?)

    @available(iOS 7.0, *)
    open func boundingRect(with size: CGSize, options: NSStringDrawingOptions = [], attributes: [NSAttributedStringKey : Any]? = nil, context: NSStringDrawingContext?) -> CGRect
}

So if you change String to NSString extension it will work

extension NSString {
    func height(withConstrainedWidth width: CGFloat, font: UIFont) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        
        let boundingBox = boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSAttributedStringKey.font: font], context: nil)
        
        return ceil(boundingBox.height)
    }
}

EDIT From Swift Team

https://bugs.swift.org/browse/SR-8408

The code in the compiler that says "NSString's members show up on String values" is specifically looking for member syntax, i.e. "foo.bar"—or in this case, "self.bar". It probably shouldn't have been written that way, but it was.

I think we'd still recommend being explicit here, even if it's ugly: (self as NSString).boundingRect(…) or let nsSelf = self as NSString; nsSelf.boundingRect(…).

edited Jun 20 '20 at 09:12

Community

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answered Jul 30 '18 at 09:08

Prashant Tukadiya

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and questions inside answers isn't suitable too – Shehata Gamal Jul 30 '18 at 09:15
Thanks Prashant. cheers! But Its really strange because it never throwing correct root cause of the problem. Anyway problem solved. – Sunil Targe Jul 30 '18 at 09:15
@Sh_Khan Do you know why this is happening / – Prashant Tukadiya Jul 30 '18 at 09:16
@SunilTarge I will update answer as soon as I came to know why self is necessary and how it is bridge NSString --- String any way thanks for accepting answer – Prashant Tukadiya Jul 30 '18 at 09:20
@PrashantTukadiya Sure! Thanks – Sunil Targe Jul 30 '18 at 09:22
1

Yes I checked. Thanks for your efforts – Sunil Targe Aug 01 '18 at 04:59

Use of unresolved identifier 'boundingRect'

1 Answers1