我在Xcode for iOS中得到了“枚举类型的隐式转换”警告，我不知道为什么

Question

With this code:

NSDataDetector *detector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingTypeLink
                                                               error:&error];

I am getting this warning:

Implicit conversion from enumeration type 'enum NSTextCheckingType' to different enumeration type 'NSTextCheckingTypes' (aka 'enum NSTextCheckingTypes')

Can someone explain to me why I am getting this warning and how to fix it?

Answer 1

+dataDetectorWithTypes: does claim to take a value from the NSTextCheckingTypes enum rather than NSTextCheckingType, but going by the rest of its documentation it should indeed allow you to specify individual values from the latter enum. I would just add a cast to NSTextCheckingTypes. You might also want to file a bug on the API.

Answer 2

Look at the docs for this method. The first parameter needs to be of type NSTextCheckingTypes . But the value you pass in, NSTextCheckingTypeLink , is of type NSTextCheckingType .

You need to pass in either NSTextCheckingAllSystemTypes , NSTextCheckingAllCustomTypes , or NSTextCheckingAllTypes .

Edit:

Upon further review, while what I stated seems correct from a parameter point of view, the rest of the docs for the method claim something else that contradicts the parameter type. Either something changed or this is a bug. Someone should report this to Apple.

Further edit:

One workaround would be to make use of a cast:

NSDataDetector *detector = 
    [NSDataDetector dataDetectorWithTypes:(NSTextCheckingTypes)NSTextCheckingTypeLink
    error:&error];