不推荐使用sizeWithFont：constrainedToSize：lineBreakMode

Question

I have the following code:

float height = [string sizeWithFont:[UIFont systemFontOfSize:kFontSize] constrainedToSize:CGSizeMake(widthOfTextView, 999999.0f) lineBreakMode:NSLineBreakByWordWrapping].height + verticalPadding;

However, whenever I run my application and get a warning telling me that this is deprecated. What should I use and how would I use it with my current code?

Thanks!

Answer 1

sizeWithFont:ConstrainedToSize:lineBreakMode is deprecated as of iOS 7, so I've also been searching high and low for the replacement. This seems to be the best answer I've found so far:

https://stackoverflow.com/a/18746573/1275947

Answer 2

This is replaced by [string boundingRectWithSize:options:attributes:context]. The "trick" is to create an attributes dictionary that contains the font and line-break mode you were previously using. In your case, that should be:

// Create a paragraph style with the desired line break mode
NSMutableParagraphStyle *paragraphStyle = [[[NSMutableParagraphStyle alloc] init] autorelease];
paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;

// Create the attributes dictionary with the font and paragraph style
NSDictionary *attributes = @{
                               NSFontAttributeName:detailTextFont,
                               NSParagraphStyleAttributeName:paragraphStyle
                           };

// Call boundingRectWithSize:options:attributes:context for the string 
CGRect textRect = [string boundingRectWithSize:CGSizeMake(widthOfTextView, 999999.0f)
                                       options:NSStringDrawingUsesLineFragmentOrigin
                                    attributes:attributes
                                       context:nil];

float height = textRect.size.height;

If you leave off the paragraph style, you will get the default of NSLineBreakByWordWrapping.

Answer 3

You actually don't need to run away from recent deprecated code that much. Its just what it says, there is a supposedly better replacement, but you should beware that only iOS7 can use it. Market usually demands that we target at least one major version backwards... Also, some API come and go, you can wait for next major version to see if time proves the benefit to update your codebase.

Answer 4

It tells you in the docs .

It says that the method is deprecated, and then tells you what you should be using in its place.

You should be using: boundingRectWithSize:options:attributes:context: