Change font size without Change UITextView attributedText

Question

I try to change a font size in my UITextView and every time I change the attributedText was restore to default.

with this I make the middle test bold :

str = [[NSMutableAttributedString alloc] initWithAttributedString:string];

[str addAttribute:NSFontAttributeName value:newFont range:NSMakeRange(range.location, range.length)];

before: that was bold font in the middle.

after :all the text bold

I want that after the size change the bold stay where he be.

Edit :

I try with this two ways :

1)

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:currentTextViewEdit.text];
        [attributedString addAttribute:NSFontAttributeName  value:[UIFont systemFontOfSize:textSize] range:NSMakeRange(0, currentTextViewEdit.text.length)];
        currentTextViewEdit.attributedText = attributedString;

2)

currentTextViewEdit.font = [UIFont   fontWithName:currentTextViewEdit.font.fontName size:textSize];

Answer 1

As reported by @matt:
aUITextView.font => change on text property (plain text)
So switching between attributedText and text like you're doing is causing the issue.

On your other solution:
Bold effect is inside the NSFontAttributeName, it's the Font value. So if you replace it by a common font, that will remove the "bold" effect. Same for italic.

So a way to do it (not tested, by according to you it's working):
• Save the attributedText (to remember the "effects", like bold in your case)
• Save the cursor position (I didn't test, so I don't know where would go the cursor afterward)
• Change the font size keeping the previous font (may be bold of normal) to the attributed string
• Update the attributedText
• Replace the cursor

You can use a Category on UITextView with a method -(void)changeFontSize:(float)newFontSize; and then you call self instead of currentTextViewEdit.

NSMutableAttributedString *attributedString = [[currentTextViewEdit attributedText] mutableCopy];

//Save the cursor/selection
NSRange cursorRange = [currentTextViewEdit selectedRange];

//Apply to update the effects on new text typed by user?
[currentTextViewEdit setFont:[UIFont fontWithName:[[currentTextViewEdit font] fontName] size:newFontSize]];

//Update the font size
[attributedString enumerateAttribute:NSFontAttributeName
                             inRange:NSMakeRange(0, [attributedString length])
                             options:0
                          usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop) {
                              UIFont *currentfont = (UIFont*)value;
                              UIFont *newFont = [UIFont fontWithName:[currentfont fontName] size:newFontSize];
                              [attributedString addAttribute:NSFontAttributeName value:newFont range:range];
                          }];
[currentTextViewEdit setAttributedText:attributedString];

//To restaure the cursor/selection
[currentTextViewEdit setSelectedRange:cursorRange];