Convert Object-C to SWIFT textKit

Question

The following code was used in my app to change the state for text in a textview between bold and italic. I have been trying to re-write it in Swift but I keep getting compile errors. Below is the objective-C version that was provided to my in an online tutorial. Following that is my new swift version up-to the point that the method is crashing.
I would apprecaite any help that might help me understand why the compiler is complaining so much.

-(void)addOrRemoveFontTraitWithName:(NSString *)traitName andValue:(uint32_t)traitValue{
NSRange selectedRange = [_field2 selectedRange];


NSDictionary *currentAttributesDict = [_field2.textStorage attributesAtIndex:selectedRange.location
                                                                effectiveRange:nil];


UIFont *currentFont = [currentAttributesDict objectForKey:NSFontAttributeName];
UIColor *currentColor = [currentAttributesDict objectForKey:NSForegroundColorAttributeName];
UIColor *currentBGColor = [currentAttributesDict objectForKey:NSBackgroundColorAttributeName];
UIFont *currentUnderlinedText = [currentAttributesDict objectForKey:NSUnderlineStyleAttributeName];
NSMutableParagraphStyle *currentparagraphStyle = [currentAttributesDict objectForKey:NSParagraphStyleAttributeName];    //receive and set new font name



UIFontDescriptor *fontDescriptor = [currentFont fontDescriptor];


NSString *fontNameAttribute = [[fontDescriptor fontAttributes] objectForKey:UIFontDescriptorNameAttribute];
UIFontDescriptor *changedFontDescriptor;

if ([fontNameAttribute rangeOfString:traitName].location == NSNotFound) {


    uint32_t existingTraitsWithNewTrait = [fontDescriptor symbolicTraits] | traitValue;
    changedFontDescriptor = [fontDescriptor fontDescriptorWithSymbolicTraits:existingTraitsWithNewTrait];

}
else{
    uint32_t existingTraitsWithoutTrait = [fontDescriptor symbolicTraits] & ~traitValue;
    changedFontDescriptor = [fontDescriptor fontDescriptorWithSymbolicTraits:existingTraitsWithoutTrait];

}
UIFont *updatedFont = [UIFont fontWithDescriptor:changedFontDescriptor size:0.0];

//create new NSDict. called dict.
NSMutableDictionary *dict;
//call below function that returns an NSMutableDict. and places value to dict.
dict = [self checkSlectedAttributes:updatedFont SelFontColor:currentColor SelFontBGColor:currentBGColor SelunderLineState:currentUnderlinedText paragraphStyle:currentparagraphStyle];

// NSLog(@"the dict is: %@", dict);

[_field2.textStorage beginEditing];
[_field2.textStorage setAttributes:dict range:selectedRange];
[_field2.textStorage endEditing];

}

SWIFT CODE: func addOrRemoveFontTraitWithName(traitName: String!, andValue traitValue: UInt32) {

    let selectedRange : NSRange = self.textView.selectedRange

    var currentAttributesDict : NSDictionary = textView.textStorage.attributesAtIndex(selectedRange.location, effectiveRange: nil)

    var currentFont : UIFont = currentAttributesDict .objectForKey(NSFontAttributeName) as UIFont

    var currentColor : UIColor = currentAttributesDict.objectForKey(NSForegroundColorAttributeName) as UIColor
    var currentBGColor : UIColor = currentAttributesDict.objectForKey(NSBackgroundColorAttributeName) as UIColor
    var currentUnderLinedText : UIFont = currentAttributesDict.objectForKey(NSUnderlineStyleAttributeName) as UIFont
    var currentparagraphStyle : NSMutableParagraphStyle = currentAttributesDict.objectForKey(NSParagraphStyleAttributeName) as NSMutableParagraphStyle

    var fontDescriptor : UIFontDescriptor = currentFont.fontDescriptor()
    var fontNameAttribute : NSString = fontDescriptor.objectForKey(UIFontDescriptorNameAttribute) as NSString
    var changedFontDescriptor : UIFontDescriptor

    if (fontNameAttribute.rangeOfString(traitName).location == NSNotFound){
       var existingTraitsWithNewTrait : UInt32 = fontDescriptor.symbolicTraits | traitValue
        changedFontDescriptor = fontDescriptor.fontDescriptorWithSymbolicTraits(existingTraitsWithNewTrait)
    }else{

        var existingTraitsWithNewTrait : UInt32 = fontDescriptor.symbolicTraits & ~traitValue
        changedFontDescriptor = fontDescriptor.fontDescriptorWithSymbolicTraits(existingTraitsWithNewTrait)
    }

}

Answer 1

According to the docs for UIFontDescriptor's "Symbolic Font Traits", the UIFontDescriptorSymbolicTraits are defined with type uint32_t in Objective-C, but not in Swift.

Try changing your code to the following:

if fontNameAttribute.rangeOfString(traitName).location == NSNotFound {
    let existingTraitsWithNewTrait : UInt32 = fontDescriptor.symbolicTraits.rawValue | traitValue
    changedFontDescriptor = fontDescriptor.fontDescriptorWithSymbolicTraits(UIFontDescriptorSymbolicTraits(rawValue: existingTraitsWithNewTrait))
} else {
    let existingTraitsWithNewTrait : UInt32 = fontDescriptor.symbolicTraits.rawValue & traitValue
    changedFontDescriptor = fontDescriptor.fontDescriptorWithSymbolicTraits(UIFontDescriptorSymbolicTraits(rawValue: existingTraitsWithNewTrait))
}

And if you still need to access the UInt32 value of UIFontDescriptorSymbolicTraits you can request the raw value:

var existingTraitsWithNewTraitUInt32:UInt32 = existingTraitsWithNewTrait.rawValue