Cocoa get string width in pixels from font

I am trying to find the width in pixels of a string from the font and font size. I am currently using this code, but it is not working 100% of the time. Is there another way to do it?

NSSize textSize = [aTextLayer.string sizeWithAttributes:[NSDictionary dictionaryWithObjectsAndKeys:@"Bank Gothic Medium", NSFontNameAttribute, [NSNumber numb开发者_开发技巧erWithFloat:aTextLayer.fontSize], NSFontSizeAttribute, nil]];

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NSAttributedString is granted a -size method by the Application Kit Additions.

NSDictionary* attributes = [NSDictionary dictionaryWithObjectsAndKeys:
    @"Bank Gothic Medium", NSFontNameAttribute,
    [NSNumber numberWithFloat:aTextLayer.fontSize], NSFontSizeAttribute,
    nil];
NSAttributedString* attributedString = [[NSAttributedString alloc] initWithString:aTextLayer.string attributes:attributes];
NSSize size = attributedString.size;

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Here is what i use to get the size of a string...

NSSize size = [@"Some text" sizeWithAttributes:[NSDictionary dictionaryWithObject:[NSFont fontWithName:@"Helvetica Neue Bold" size:24.0f] forKey:NSFontAttributeName]];

NOTE: If you are adding the string to a textfield, i have found that you need to add about 10 to size.width for it to fit.

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Try using the actual NSFont (or UIFont) object instead of just the name of the font.

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Here is yet another example:

NSString *test = [[NSString alloc] initWithFormat:@"%u:%u:%u.000", hours, minutes, seconds];
NSSize boundingSize = {100,300};  //I suppose this is the constraints?
NSRect boundingRect = [test boundingRectWithSize:boundingSize options:NULL attributes:stringAttributes];
point.x -= boundingRect.size.width; //This point points at the end of screen
[test drawAtPoint:point withAttributes:stringAttributes];

Here is for the stringAttributes, that may help noobs like me:

NSMutableDictionary *stringAttributes;
    stringAttributes = [NSMutableDictionary dictionary];
    [stringAttributes setObject:[NSFont fontWithName:@"Monaco" size:16] forKey:NSFontAttributeName];
    [stringAttributes setObject:[NSColor whiteColor] forKey:NSForegroundColorAttributeName];
    [stringAttributes setObject:[NSColor blackColor] forKey:NSBackgroundColorAttributeName];