ivan.m 垂直式對齊 UILabel（https://discussions.apple.com/thread/1759957?tstart=0）

VerticalUILabel.m

// Label2.mm
// (c) 2009 Ivan Misuno, www.cuberoom.biz

#import "Label2.h"

@implementation Label2

-(id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (!self) return nil;
    
    _verticalAlignment = VerticalAlignmentTop;
    
    return self;
}

-(void)dealloc
{
    [super dealloc];
}

-(VerticalAlignment) verticalAlignment
{
    return _verticalAlignment;
}
-(void) setVerticalAlignment:(VerticalAlignment)value
{
    _verticalAlignment = value;
    [self setNeedsDisplay];
}

// align text block according to vertical alignment settings
-(CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines
{
    CGRect rect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];
    CGRect result;
    switch (_verticalAlignment)
    {
        case VerticalAlignmentTop:
            result = CGRectMake(bounds.origin.x, bounds.origin.y, rect.size.width, rect.size.height);
            break;
        case VerticalAlignmentMiddle:
            result = CGRectMake(bounds.origin.x, bounds.origin.y + (bounds.size.height - rect.size.height) / 2, rect.size.width, rect.size.height);
            break;
        case VerticalAlignmentBottom:
            result = CGRectMake(bounds.origin.x, bounds.origin.y + (bounds.size.height - rect.size.height), rect.size.width, rect.size.height);
            break;
        default:
            result = bounds;
            break;
    }
    return result;
}

-(void)drawTextInRect:(CGRect)rect
{
    CGRect r = [self textRectForBounds:rect limitedToNumberOfLines:self.numberOfLines];
    [super drawTextInRect:r];
}

@end