UILabel sizeThatFits too wide for 1-line label - ios

Question

I have a label that I'm creating and displaying programmatically. It can be 1 or more lines. I want to the label to be truncated at the end if it's too long. When the label is > 1 line long the following code works fine. Create a blank project and drop this into viewDidLoad to play along at home. Any iOS or tvOS project should do.
UILabel *label = [[UILabel alloc] initWithFrame:CGRectZero];
label.numberOfLines = 2;
label.lineBreakMode = NSLineBreakByTruncatingTail;
label.backgroundColor = [UIColor blueColor];
[self.view addSubview:label];
NSDictionary *attributes = #{NSFontAttributeName:[UIFont systemFontOfSize:26.0]};
label.attributedText = [[NSAttributedString alloc] initWithString:#"The rain in Spain falls mainly on the plain." attributes:attributes];
CGSize maxLabelSize = CGSizeMake(200, CGFLOAT_MAX);
CGSize requiredSize = [label sizeThatFits:maxLabelSize];
NSLog(#"requiredSize: %#", NSStringFromCGSize(requiredSize));
label.frame = CGRectMake(50.0, 50.0, requiredSize.width, requiredSize.height);
However, if I change numberOfLines to 1 then sizeThatFits returns a size with a width wide enough to fit the entire string even though it's bigger than the width of maxLabelSize.
I can work around this by checking to see if requiredSize.width is greater than maxLabelSize.width, and adjusting appropriately, but I'd like to know why sizeThatFits behaves differently with a 1-line label than with a multi-line label. I would expect a size no greater than 200 with the height the same as the attributed string's line height.

Answer 1

I have no idea why sizeThatFits doesn't work, but another method textRectForBounds:limitedToNumberOfLines: does the trick. Something like
label.numberOfLines = 0;
CGSize requiredSize = [label textRectForBounds:CGRectMake(0, 0, 200, CGFLOAT_MAX) limitedToNumberOfLines:1].size;

Answer 2

UILabel * commlbl;
commlbl=[[UILabel alloc]initWithFrame:CGRectMake(10, commlbl1.bounds.size.height+50, commscroll.bounds.size.width-25, commscroll.bounds.size.height+70)];
[commlbl setFont:[UIFont fontWithName:#"OpenSans-Regular" size:16]];
[commlbl setTextColor:[UIColor whiteColor]];
[commlbl setTextAlignment:NSTextAlignmentCenter];
commlbl.lineBreakMode = NSLineBreakByWordWrapping;
commlbl.numberOfLines = 0;
commlbl.text = [USER_DFT GetUserDefault:#"msgString"];
CGSize maximumLabelSize = CGSizeMake(296, FLT_MAX);
CGSize expectedLabelSize = [commlbl.text sizeWithFont:commlbl.font constrainedToSize:maximumLabelSize lineBreakMode:commlbl.lineBreakMode];
//adjust the label the the new height.
CGRect newFrame = commlbl.frame;
newFrame.size.height = expectedLabelSize.height;
commlbl.frame = newFrame;