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在iOS中默认的UILabel中的文字在竖直方向上只能居中对齐，我从UILabel继承了一个新类，实现了居上对齐，居中对齐，居下对齐。具体如下：
1.新建一个类VerticalAlignmentLabel.h继承自UILabel
2.
//
// VerticalAlignmentLabel.h
// inface
//
// Created by huangzengsong on 15/5/10.
// Copyright (c) 2015年 huangzs. All rights reserved.
//
#import <UIKit/UIKit.h>
typedef enum
{
VerticalAlignmentTop = 0, // default
VerticalAlignmentMiddle,
VerticalAlignmentBottom,
} VerticalAlignment;
@interface VerticalAlignmentLabel : UILabel
{
@private
VerticalAlignment _verticalAlignment;
}
@property (nonatomic) VerticalAlignment verticalAlignment;
@end
3.
//
// VerticalAlignmentLabel.m
// inface
//
// Created by huangzengsong on 15/5/10.
// Copyright (c) 2015年 huangzs. All rights reserved.
//
#import "VerticalAlignmentLabel.h"
@implementation VerticalAlignmentLabel
@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];
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// Drawing code
}
*/
@end
4.调用时导入头文件
#import "VerticalAlignmentLabel.h"
5.
[self.DetailLabel setVerticalAlignment:VerticalAlignmentTop];
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原文地址：http://www.cnblogs.com/huangzs/p/4493173.html
