Computing for text height is buggy on iOS 7

Question

I have a piece of code that computes for the height a block of text is going to use up and set the uiLabel accordingly:

text = [self tableText:[indexPath row] forIndex:index];
constraint = CGSizeMake(detailWidth, 20000.0f);
size = [text sizeWithFont:[UIFont systemFontOfSize:16.0f] constrainedToSize:constraint lineBreakMode:NSLineBreakByWordWrapping];

UILabel *presidentDetailLabel = (UILabel *)[cell viewWithTag:200];
[presidentDetailLabel setFrame:CGRectMake(presidentDetailLabel.frame.origin.x, presidentDetailLabel.frame.origin.y, presidentDetailLabel.frame.size.width, MAX(size.height, presidentDetailLabel.frame.size.height))];
[presidentDetailLabel setText:text];

The code works fine on iOS 6 but when I compiled it on iOS 7 and ran it on an emulator. The size returned seems to be a few pixels short. I actually have a NSlog to check if the fontsize and the value returned is 16.

Same problem with a similar block of code only this time I'm using attributed string and it still returns a height a few pixels short. From what I gather. It seems that the text is using up the space equivalent of font size 17.

Any advice how to hunt this bug down?

Answer 1

I fixed my problem using this code:

NSString *text = [self tableText:[indexPath row] forIndex:index];

UILabel *presidentDetailLabel = (UILabel *)[cell viewWithTag:200];
[presidentDetailLabel setText:text];

CGSize size = [presidentDetailLabel sizeThatFits:CGSizeMake(presidentDetailLabel.frame.origin.y, 2000)];
[presidentDetailLabel setFrame:CGRectMake(presidentDetailLabel.frame.origin.x, presidentDetailLabel.frame.origin.y, presidentDetailLabel.frame.size.width, size.height)];

Answer 2

I am using following lines in some of my projects and always work like charm in iOS 5 and above (didn't use in lower versions).

CGSize constraint = CGSizeMake(label.frame.size.width, 2000.0f);

CGSize size;

NSStringDrawingContext *context     = [[NSStringDrawingContext alloc] init];

CGSize boundingBox = [label.text boundingRectWithSize:constraint
                                              options:NSStringDrawingUsesLineFragmentOrigin
                                           attributes:@{NSFontAttributeName:label.font}
                                              context:context].size;

size = CGSizeMake(ceil(boundingBox.width), ceil(boundingBox.height));

[label setFrame:CGRectMake(label.frame.origin.x, label.frame.origin.y, label.frame.size.width, size.height)];