ios UILabel设置居上对齐，居中对齐，居下对齐

最新推荐文章于 2020-12-19 18:02:08 发布

Coding-lover

最新推荐文章于 2020-12-19 18:02:08 发布

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本文介绍如何在iOS中通过继承UILabel类，实现UILabel的文字在竖直方向上的居中对齐、居上对齐和居下对齐功能。通过设置垂直对齐属性，可以灵活调整UILabel显示效果。

在iOS中默认的UILabel中的文字在竖直方向上只能居中对齐，博主参考国外网站，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：

//  
//  myUILabel.h  
//    
//  
//  Created by yexiaozi_007 on 3/4/13.  
//  Copyright (c) 2013 yexiaozi_007. All rights reserved.  
//  
  
#import <UIKit/UIKit.h>  
typedef enum  
{  
    VerticalAlignmentTop = 0, // default  
    VerticalAlignmentMiddle,  
    VerticalAlignmentBottom,  
} VerticalAlignment;  
@interface myUILabel : UILabel  
{  
@private  
VerticalAlignment _verticalAlignment;  
}  
  
@property (nonatomic) VerticalAlignment verticalAlignment;  
  
@end

//  
//  myUILabel.m  
//    
//  
//  Created by yexiaozi_007 on 3/4/13.  
//  Copyright (c) 2013 yexiaozi_007. All rights reserved.  
//  
  
#import "myUILabel.h"  
  
@implementation myUILabel  
@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

在使用时：

lbl_mylabel = [[myUILabel alloc] initWithFrame:CGRectMake(20, 50, 150, 600)];  
UIColor *color = [UIColor colorWithPatternImage:[UIImage imageNamed:@"halfTransparent.png"]];//使用半透明图片作为label的背景色  
lbl_mylabel.backgroundColor = color;  
lbl_mylabel.textAlignment = UITextAlignmentLeft;  
lbl_mylabel.textColor = UIColor.whiteColor;  
lbl_mylabel.lineBreakMode = UILineBreakModeWordWrap;  
lbl_mylabel.numberOfLines = 0;  
[lbl_mylabel setVerticalAlignment:VerticalAlignmentTop];  
[self addSubview:lbl_mylabel];

转载自： http://blog.youkuaiyun.com/yexiaozi_007/article/details/8636522