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iOS中UILabel设置居上对齐、居中对齐、居下对齐及文字置顶显示
    点击次数:  更新时间:2017-12-19 08:28:16  【打印此页】  【关闭

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:

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//

// 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

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//

// 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:

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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];

UILabel 让文字置顶显示

我们经常会遇到将Label中文字置顶,也就是将文字顶到Lable框的最顶端显示的需求,UILabel是无法对内容文字进行置顶处理的,所以,如果我们不对Label加以额外的设置,就会出现如下情况: