bold, italic using UIFontDescriptor - ios

Question

i have an UITextView that have some text and 2 buttons one to make selected texet bold anthor to make it italic
- (IBAction)boldedSelectedText:(UIButton*)sender {
UIFontDescriptor* bodyFontDescriptor=[UIFontDescriptor preferredFontDescriptorWithTextStyle:UIFontTextStyleBody];
UIFontDescriptor* boldFontdescriptor=[bodyFontDescriptor fontDescriptorWithSymbolicTraits:UIFontDescriptorTraitBold];
self.body.font=[UIFont fontWithDescriptor:boldFontdescriptor size:0.0];
}
- (IBAction)italicSelectedText:(UIButton *)sender {
UIFontDescriptor* bodyFontDescriptor=[UIFontDescriptor preferredFontDescriptorWithTextStyle:UIFontTextStyleBody];
UIFontDescriptor* italicFontdescriptor=[bodyFontDescriptor fontDescriptorWithSymbolicTraits:UIFontDescriptorTraitItalic];
self.body.font=[UIFont fontWithDescriptor:italicFontdescriptor size:0.0];
}
the problem is when i select a text and make it bold then italic , it become italic only and vice
it can not be bold and italic at the same time i don't know why?

Answer 1

You need to retrieve the existing symbolic traits first, then add your new trait.
I use a helper method to add/remove my traits,
-(void) addOrRemoveFontTraitWithName:(NSString*)traitName andValue:(uint32_t)traitValue
{
NSMutableDictionary *attributes;
NSRange selectedRange=[self.attributedTextview selectedRange];
if (selectedRange.length == 0)
{
//no text selected
attributes=[[NSMutableDictionary alloc] initWithDictionary:self.attributedTextview.typingAttributes];
}
else
{
attributes=[[NSMutableDictionary alloc] initWithDictionary:[self.attributedTextview.textStorage attributesAtIndex:selectedRange.location effectiveRange:nil]];
}
UIFont *currentFont=[attributes objectForKey:NSFontAttributeName];
UIFontDescriptor *fontDescriptor=[currentFont fontDescriptor];
NSString *fontNameAttribute=[[fontDescriptor fontAttributes] objectForKey:UIFontDescriptorNameAttribute];
UIFontDescriptor *changedFontDescriptor;
if ([fontNameAttribute containsString:traitName])
{
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];
[attributes setObject:updatedFont forKey:NSFontAttributeName];
if (selectedRange.length != 0)
{
[self.attributedTextview.textStorage beginEditing];
[self.attributedTextview.textStorage setAttributes:attributes range:selectedRange];
[self.attributedTextview.textStorage endEditing];
}
[self.attributedTextview setTypingAttributes:attributes];
}
If the user has selected some text, the trait is applied to that specific selection, otherwise it is applied to the textview's typingAttributes property.
A bitwise operation is required to add/remove the trait.
This article covers this subject in some detail and is well worth a read
Using Text Kit to Manage and Draw Text in IOS Apps
Regards