Calculate UILabel height gives wrong values - objective-c

Question

I am trying to "forecast" what the size of a label is going to be (width is known, only height).
I am trying to use this:
CGSize possibleSize = [text sizeWithFont:[UIFont fontWithName:#"American Typewriter" size:16]
constrainedToSize:CGSizeMake(self.collectionView.frame.size.width ,9999)
lineBreakMode:NSLineBreakByWordWrapping];
Which gives very inaccurate results (even changing the fonts and the size won't make it better, for example I get the height 30 instead of 80).
I have read that other people also don't get good results with it. Am I using it right?
I have also tried:
UILabel *test=[[UILabel alloc] initWithFrame:self.collectionView.frame];
test.text=[dic objectForKey:#"text"];
test.font=[UIFont fontWithName:#"American Typewriter" size:12];
[test sizeToFit];
NSLog(#"%f",test.frame.size.height);
I have to know what the height is going to be, and this method is not even close.
Is there some other way that gives reasonable results?

Answer 1

This sizeWithFont method is now deprecated, this new method works best
NSString *content = **Whatever your label's content is expected to be**
CGSize maximumLabelSize = CGSizeMake(self.label.frame.size.width, 9999);
NSDictionary *stringAttributes = [NSDictionary dictionaryWithObject:[UIFont fontWithName:#"American Typewriter" size:16] forKey: NSFontAttributeName];
CGSize expectedLabelSize = [content boundingRectWithSize:maximumLabelSize options:NSStringDrawingTruncatesLastVisibleLine|NSStringDrawingUsesLineFragmentOrigin attributes:stringAttributes context:nil].size;
CGFloat labelHeight = expectedLabelSize.height;
where labelHeight is the height that the label will be calculated from the amount of text due to load into the label.
I hope this helps, cheers, Jim.

Answer 2

#matt you are onto something, but I'll add that you should set the number of lines on that label to 0, before you calculate sizeWithFont.
You may also try to replace
CGSizeMake(self.collectionView.frame.size.width ,9999)
with
CGSizeMake(self.collectionView.bounds.size.width ,FLT_MAX)
the key element being "bounds" instead of frame.
Lastly, ensure you're not getting nothing for [dic objectForKey:#"text"].
Use
NSAssert(dic[#"text"]);
if ([dic[#"text"] isEqualToString:""]) {
; //empty string
}

Answer 3

First of all you need to allow a UILabel to be multiline, by default it is one line (set number of line to 0)
yourLabel.numberOfLines = 0; // means - label can be multiline
Secondly, it looks like you are calculating size for a bigger font that the label has in fact. Consider using the same size so set the calculations correctly.
Moreover if you support only iOS 7 and newer consider usage of sizeWithAttributes method introduced in iOS 7 or boundingRectWithSize:options:attributes:context - replacement for the method you use from iOS 7 and further for text size calculations.
Finally (advice) if you need that height value only for setting height of the label maybe you should consider using auto layout (it will be much easier to deal with).