demo效果图:

Paste_Image.png

使用方式:

1>将"MyLable"拖到项目中,需要调用的地方导入头文件

Paste_Image.png

MyLable.h文件

#import <UIKit/UIKit.h>
typedef enum
{
    VerticalAlignmentTop = 0, // default
    VerticalAlignmentMiddle,
    VerticalAlignmentBottom,
} VerticalAlignment;
@interface MyLable : UILabel
{
@private
    VerticalAlignment _verticalAlignment;
}

@property (nonatomic) VerticalAlignment verticalAlignment;

-(void)setVerticalAlignment:(VerticalAlignment)verticalAlignment;
@end

MyLable.m文件

#import "MyLable.h"

@implementation MyLable
@synthesize verticalAlignment = verticalAlignment_;

-(id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.verticalAlignment = VerticalAlignmentMiddle;
    }
    return self;
}

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



-(CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines {
    CGRect textRect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];
    switch (self.verticalAlignment) {
        case VerticalAlignmentTop:
            textRect.origin.y = bounds.origin.y;
            break;
        case VerticalAlignmentBottom:
            textRect.origin.y = bounds.origin.y + bounds.size.height - textRect.size.height;
            break;
        case VerticalAlignmentMiddle:
            // Fall through.
        default:
            textRect.origin.y = bounds.origin.y + (bounds.size.height - textRect.size.height) / 2.0;
    }
    return textRect;
}

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



@end

2>一句代码调用,例如

居上对齐

居中对齐

居下对齐

感谢原作者的demo,以下是参考来源:
http://code.cocoachina.com/view/134318
https://github.com/OwenJoe/LableAlignment.git