问题
I am having some trouble with Swift code in a library I have been using for a while. It seems related to some kind of version conflict, but I am not sure.
Here is the code:
let attribMsg = NSAttributedString(string: msg,
attributes: [NSAttributedStringKey.font:UIFont.systemFont(ofSize: 23.0)])
Here is the error message I get from the compiler:
Type 'NSAttributedStringKey' (aka 'NSString') has no member 'font'
Did you mean 'zone'? Fix(button)
Using this code in different project I noticed that on some of them I do not get the error message and it all compiles without any problem.
I also noticed that if I replace the above code by the following:
let attribMsg = NSAttributedString(string: msg,
attributes: [NSFontAttributeName:UIFont.systemFont(ofSize: 23.0)])
The projects with a problem will work while the others(previously working) show this other message:
'NSFontAttributeName' has been renamed to 'NSAttributedStringKey.font'
In other words some projects work with one type of code and some others work with the other type.
Needless to say that I do not want to change the code each time I switch from one project to another.
The experiments I made changing the Deployment Target of the project do not seem to make much difference. So comes my question: What is the way to handle this issue?
回答1:
The projects are probably in different versions of Swift.
In Swift 4, NSFontAttributeName has been replaced with NSAttributedStringKey.font.
回答2:
Swift 4.2
NSAttributedStringKey renamed NSAttributedString.Key. However for this particular issue you need to get the raw value so the solution would be NSAttributedString.Key.font.rawValue
Take a look here for an in-depth explanation: https://stackoverflow.com/a/46459315/2440997
来源：https://stackoverflow.com/questions/46966681/nsfontattributename-vs-nsattributedstringkey-font