iOS-7-boundingRectWithSize-options-attributes-context.m

NSString* string = @"Hello World"; 

UIFont *font = [UIFont fontWithName:@"Helvetica-BoldOblique" size:21];

CGSize constraint = CGSizeMake(300,NSUIntegerMax);

NSDictionary *attributes = @{NSFontAttributeName: font};

CGRect rect = [string boundingRectWithSize:constraint 
                                   options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)  
                                attributes:attributes 
                                   context:nil];

// Construct your label

UILabel* label = [[UILabel alloc] initWithFrame:rect];

[label setText:string];
 
[label setTextAlignment:NSTextAlignmentRight];

label.lineBreakMode = NSLineBreakByWordWrapping;

label.numberOfLines = 0;

[label setFont:font];