iOS的UILabel設置居上對齊，居中對齊，居下對齊

前言：

沒有理由不去努力.png

正文：
想實現UILabel居上對齊，居中對齊，居下對齊，如下效果：

效果圖.png

在iOS中默認的UILabel中的文字在豎直方向上只能居中對齊，博主參考國外網站，從UILabel繼承了一個新類，實現了居上對齊，居中對齊，居下對齊

具體如下：

創建：MYLabel 繼承與UILabel

在MYLabel.h中完成

在MYLabel.h中完成

// // MYLabel.h // LabelDemo // // Created by wangergang on 2016/12/7. // Copyright © 2016年 MYCompangName. All rights reserved. // #import <UIKit/UIKit.h> typedef enum { VerticalAlignmentTop = 0, //default VerticalAlignmentMiddle, VerticalAlignmentBottom, } VerticalAlignment; @interface MYLabel : UILabel { @private VerticalAlignment _verticalAlignment; } @property (nonatomic) VerticalAlignment verticalAlignment; @end

在MYLabel.m中完成

在MYLabel.m中完成

// // MYLabel.m // LabelDemo // // Created by wangergang on 2016/12/7. // Copyright © 2016年 MYCompangName. All rights reserved. // #import "MYLabel.h" @implementation MYLabel @synthesize verticalAlignment = verticalAlignment_; - (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { self.verticalAlignment = VerticalAlignmentMiddle; } return self; } - (void)setVerticalAlignment:(VerticalAlignment)verticalAlignment { verticalAlignment_ = verticalAlignment; [self setNeedsLayout]; } - (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

使用：首先記得引入頭文件

import "MYLabel.h"

- (void)viewDidLoad { [super viewDidLoad]; [self setupLabel]; // Do any additional setup after loading the view, typically from a nib. } - (void)setupLabel { //居上對齊 MYLabel *topLabel = [[MYLabel alloc] initWithFrame:CGRectMake(20, 275, 350, 200)]; topLabel.text = @"劇終了、劇終了、劇終了、劇終了、劇終了、劇終了、劇終了、"; topLabel.backgroundColor = [UIColor cyanColor]; topLabel.textAlignment = NSTextAlignmentLeft; topLabel.textColor = [UIColor blueColor]; topLabel.lineBreakMode = NSLineBreakByCharWrapping; topLabel.numberOfLines = 0; [topLabel setVerticalAlignment:VerticalAlignmentMiddle]; [self.view addSubview:topLabel]; //居中對齊 MYLabel *middleLabel = [[MYLabel alloc] initWithFrame:CGRectMake(20, 500, 350, 200)]; middleLabel.text = @"向下看、向下看、向下看、向下看、向下看、向下看、向下看、向下看、"; middleLabel.backgroundColor = [UIColor cyanColor]; middleLabel.textAlignment = NSTextAlignmentLeft; middleLabel.textColor = [UIColor blueColor]; middleLabel.lineBreakMode = NSLineBreakByCharWrapping; middleLabel.numberOfLines = 0; [middleLabel setVerticalAlignment:VerticalAlignmentBottom]; [self.view addSubview:middleLabel]; //居下對齊 MYLabel *bottomLabel = [[MYLabel alloc] initWithFrame:CGRectMake(20, 50, 350, 200)]; bottomLabel.text = @"看我居上對齊了啊、你看看對不對的啊、看來是對的"; bottomLabel.backgroundColor = [UIColor cyanColor]; bottomLabel.textAlignment = NSTextAlignmentLeft; bottomLabel.textColor = [UIColor blueColor]; bottomLabel.lineBreakMode = NSLineBreakByCharWrapping; bottomLabel.numberOfLines = 0; [bottomLabel setVerticalAlignment:VerticalAlignmentTop]; [self.view addSubview:bottomLabel]; }

其效果圖如上圖：就不再上傳了

Demo位置github位置