我如何在NIAttributedLabel中正确使用NSString sizeWithFont constratinedToSize

Question

I've gone over what feels like every post about this method on SO. And a lot of the posters answers are to just put a really large value as the height constraint.

However, for me this is not working. This is my code:

//Create the contentLabel Label
    CGSize size = [contentText sizeWithFont:[UIFont fontWithName:@"Helvetica" size:14] constrainedToSize:CGSizeMake(286, 9999) lineBreakMode:UILineBreakModeWordWrap];

    //Create the content label with its position 7 pixels below the title 
    contentLabel = [[NIAttributedLabel alloc] initWithFrame:
                   CGRectMake(7, titleContainerView.frame.origin.y + 7, 286, size.height)];

    //Set the provided text and the font
    contentLabel.font = [UIFont fontWithName:@"Helvetica" size:14];
    contentLabel.numberOfLines = 0;
    contentLabel.lineBreakMode = UILineBreakModeWordWrap;
    contentLabel.text = contentText;

I am using NIAttributedLabel , thought this shouldn't really have an effect because the method returning what I believe to be the wrong size is part of NSString .

\n

I did read in Apple's documentation that the method will truncate the string sometimes, though I thought thats what the large height constraint was for

EDIT: I've discovered that it is an issue with NIAttributedLabel , If I use a regular UILabel it works perfectly. Here are two source strings and corresponding screenshots, the first demonstrating my issue, the other deciding to be fine:

"Buying a Mobile\\nHello - I'd like a Motorola Defy with a Smartphone 60 Plan.\\nBroadband Problem\\nMy Broadband's out. I've tested the router and cables and ruled out my equipment. Is there a problem at your end?"

"Buying a Mobile\\nI\\'m Mrs Sina Manu-Harris. My account number is 156205169. I\\'m going overseas in 6 months time on the 2nd of September and I\\'d like to get organized in advance and buy a new mobile phone.\\nBroadband Problem\\nGood afternoon. It's Mrs Sina Manu-Harris here. My account number is 156205169. My Broadband isn't working. I've checked my network and phone cables and I've also checked my filters."

Answer 1

NimbusKit 1.0 provide a new method for calculating height of NIAttributedLabel: NISizeOfAttributedStringConstrainedToSize()

I used to use sizeWithFont: and encounter same problem as you. Now the new method worked for me perfectly (I don't have any images in my attriubited label)

Answer 2

You can't depend on NSString using the same glyph placement algorithm that CoreText will. When sizing NIAttributedLabel it is recommended that you use the label's sizeToFit and sizeThatFits: methods because they use CoreText to determine the ideal size of the label.

Answer 3

Please check with string @"T\\nT\\nT", it will only prints @"T\\nT\\n". It seems _textFrame only shows two visible lines instead of three.