'sizeWithFont:constrainedToSize:lineBreakMode:'is deprecated:

Question 1

I wouldn't just mask the deprecated function warning. They deprecated it for a reason. I believe the function was deprecated because that series of NSString+UIKit functions were based on the UIStringDrawing library, which wasn't thread safe. If you tried to run them not on the main thread (like any other UIKit functionality), you'll get unpredictable behaviors. In particular, if you ran the function on multiple threads simultaneously, it'll probably crash your app. This is why in iOS 6, they introduced a the boundingRectWithSize:... method for NSAttributedStrings. This was built on top of the NSStringDrawing libraries and is thread safe.

If you look at the new NSString boundingRectWithSize:... function, it asks for an attributes array in the same manner as a NSAttributeString. If I had to guess, this new NSString function in iOS 7 is merely a wrapper for the NSAttributeString function from iOS 6.

On that note, if you were only supporting iOS 6 and iOS 7, then I would definitely change all of your NSString's sizeWithFont:... to the NSAttributeString's boundingRectWithSize. It'll save you a lot of headache if you happen to have a weird multi-threading corner case! Here's how I converted NSString's sizeWithFont:constrainedToSize::

What used to be:

NSString *text = ...;
CGFloat width = ...;
UIFont *font = ...;
CGSize size = [text sizeWithFont:font 
               constrainedToSize:(CGSize){width, CGFLOAT_MAX}];

Can be replaced with:

NSString *text = ...;
CGFloat width = ...;
UIFont *font = ...;
NSAttributedString *attributedText =
    [[NSAttributedString alloc]
        initWithString:text
        attributes:@
        {
            NSFontAttributeName: font
        }];
CGRect rect = [attributedText boundingRectWithSize:(CGSize){width, CGFLOAT_MAX}
                                           options:NSStringDrawingUsesLineFragmentOrigin
                                           context:nil];
CGSize size = rect.size;

Please note the documentation mentions:

In iOS 7 and later, this method returns fractional sizes (in the size component of the returned CGRect); to use a returned size to size views, you must use raise its value to the nearest higher integer using the ceil function.

So to pull out the calculated height or width to be used for sizing views, I would use:

CGFloat height = ceilf(size.height);
CGFloat width  = ceilf(size.width);

Question 2

If you want it compatible with both iOS7 and the versions below it, try this one (with ARC):

CGSize size;

if ([tempPointStr respondsToSelector:
     @selector(boundingRectWithSize:options:attributes:context:)])
{
  NSMutableParagraphStyle * paragraphStyle = [[NSMutableParagraphStyle alloc] init];
  paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
  paragraphStyle.alignment = NSTextAlignmentLeft;

  NSDictionary * attributes = @{NSFontAttributeName : self.lblHidden.font,
                      NSParagraphStyleAttributeName : paragraphStyle};

  size = [tempPointStr boundingRectWithSize:self.lblHidden.frame.size
                                    options:NSStringDrawingUsesFontLeading
                                           |NSStringDrawingUsesLineFragmentOrigin
                                 attributes:attributes
                                    context:nil].size;
} else {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
  size = [tempPointStr sizeWithFont:self.lblHidden.font
                  constrainedToSize:self.lblHidden.frame.size
                      lineBreakMode:NSLineBreakByWordWrapping];
#pragma clang diagnostic pop
}

Note: It's just an example for your else-if case, maybe you need to do some modification depend on what you want it be. ;)

Question 3

For iOS7, replace:

CGSize size = [tempPointStr sizeWithFont:self.lblHidden.font
                       constrainedToSize:self.lblHidden.frame.size
                           lineBreakMode:NSLineBreakByWordWrapping];

With:

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];
paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping; //set the line break mode
NSDictionary *attrDict = [NSDictionary dictionaryWithObjectsAndKeys:self.lblHidden.font, NSFontAttributeName, paragraphStyle, NSParagraphStyleAttributeName, nil];
CGSize size = [tempPointStr boundingRectWithSize:self.lblHidden.frame.size
                                         options:NSStringDrawingTruncatesLastVisibleLine|NSStringDrawingUsesLineFragmentOrigin
                                      attributes:attrDict context:nil].size;

Question 4

You can use:

UIFont *font = [UIFont boldSystemFontOfSize:16];

CGRect new = [string boundingRectWithSize:CGSizeMake(200, 300)
    options:NSStringDrawingUsesFontLeading 
    attributes:@{NSFontAttributeName: font} 
    context:nil];

CGSize stringSize= new.size;

Question 5

If you're targeting iOS 6.0+, you can still use sizeWithFont:constrainedToSize:lineBreakMode:. Just make sure that your project's iOS Deployment Target is set for 6.0, and the compiler won't give you these warnings.

(You can find this by clicking on the blue project tab (usually at the top of the left, project navigator pane) within the "info" section).

If you're only targeting iOS 7.0+, you should use the new method boundingRectWithSize:options:attributes:context.

You can find the Apple docs on this new method here.

Question 6

The boundingRectWithSize:options:attributes:context has the problem, that it does not calculates the height correctly if the String contains "\n" (line breaks). Therefore this code calculates the size for each line separately for a given width (inWidth):

NSArray *brokenByLines=[string componentsSeparatedByString:@"\n"];
CGFloat height=0.0;
CGFloat maxWidth=0.0;
for (NSString* actString in brokenByLines) {
    CGRect tSize=[actString boundingRectWithSize:CGSizeMake(inWidth, 600) options:(NSStringDrawingUsesLineFragmentOrigin | NSLineBreakByWordWrapping) attributes:@{NSFontAttributeName: inFont} context:nil];
    if (maxWidth<tSize.size.width) {
        maxWidth=tSize.size.width;
    }
    height+=tSize.size.height;
}
CGSize size= CGSizeMake(ceil(maxWidth), ceil(height));