iOS开发Label文字显示位置上、中、下

在系统自带的UILabel中是没有吸顶及吸底部的方法的（如果有请告诉我，我没找到），于是乎重写label

 1 //
 2 //  gzhVerticalAlignmentLabel.h
 3 //  VerticalAlignmentLabel
 4 //
 5 //  Created by 郭志贺 on 2020/6/1.
 6 //  copyright © 2020 郭志贺. All rights reserved.
 7 //
 8 
 9 #import <UIKit/UIKit.h>
10 
11 NS_ASSUME_NONNULL_BEGIN
12 
13 typedef enum VerticalAlignment {
14 
15     VerticalAlignmentTop,
16 
17     VerticalAlignmentMiddle,
18 
19     VerticalAlignmentBottom,
20 
21 } VerticalAlignment;
22 
23 @interface gzhVerticalAlignmentLabel : UILabel{
24 
25 @private VerticalAlignment verticalAlignment_;
26 
27 }
28 
29 
30 
31 @property (nonatomic, assign) VerticalAlignment verticalAlignment;
32 
33 @end
34 
35 NS_ASSUME_NONNULL_END

 1 //
 2 //  gzhVerticalAlignmentLabel.m
 3 //  VerticalAlignmentLabel
 4 //
 5 //  Created by 郭志贺 on 2020/6/1.
 6 //  copyright © 2020 郭志贺. All rights reserved.
 7 //
 8 
 9 #import "gzhVerticalAlignmentLabel.h"
10 
11 @implementation gzhVerticalAlignmentLabel
12 
13 @synthesize verticalAlignment = verticalAlignment_;
14 
15 
16 
17 
18 - (void)setVerticalAlignment:(VerticalAlignment)verticalAlignment {
19 
20     verticalAlignment_ = verticalAlignment;
21 
22     [self setNeedsdisplay];
23 
24 }
25 
26 
27 
28 - (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines {
29 
30     CGRect textRect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];
31 
32     switch (self.verticalAlignment) {
33 
34         case VerticalAlignmentTop:
35 
36             textRect.origin.y = bounds.origin.y;
37 
38             break;
39 
40         case VerticalAlignmentBottom:
41 
42             textRect.origin.y = bounds.origin.y + bounds.size.height - textRect.size.height;
43 
44             break;
45 
46         case VerticalAlignmentMiddle:
47 
48 
49         default:
50 
51             textRect.origin.y = bounds.origin.y + (bounds.size.height - textRect.size.height) / 2.0;
52 
53     }
54 
55     return textRect;
56 
57 }
58 
59 
60 
61 -(void)drawTextInRect:(CGRect)requestedRect {
62 
63     CGRect actualRect = [self textRectForBounds:requestedRect limitedToNumberOfLines:self.numberOfLines];
64 
65     [super drawTextInRect:actualRect];
66 
67 }
68 
69 @end

使用方式

 1 //
 2 //  ViewController.m
 3 //  VerticalAlignmentLabel
 4 //
 5 //  Created by 郭志贺 on 2020/6/1.
 6 //  copyright © 2020 郭志贺. All rights reserved.
 7 //
 8 
 9 #import "ViewController.h"
10 #import "gzhVerticalAlignmentLabel.h"
11 
12 /** 屏幕高度 */
13 #define ScreenH [UIScreen mainScreen].bounds.size.height
14 /** 屏幕宽度 */
15 #define ScreenW [UIScreen mainScreen].bounds.size.width
16 
17 @interface ViewController ()
18 
19 @property(nonatomic,strong)gzhVerticalAlignmentLabel * topLabel;
20 @property(nonatomic,strong)gzhVerticalAlignmentLabel * centerLabel;
21 @property(nonatomic,strong)gzhVerticalAlignmentLabel * bottomLabel;
22 
23 @end
24 
25 @implementation ViewController
26 
27 - (void)viewDidLoad {
28     [super viewDidLoad];
29     // Do any additional setup after loading the view.
30     
31     _topLabel = [[gzhVerticalAlignmentLabel alloc]initWithFrame:CGRectMake((ScreenW-200)/2.0, 100, 200, 80)];
32     _topLabel.verticalAlignment = VerticalAlignmentTop;
33     _topLabel.backgroundColor = [UIColor redColor];
34     _topLabel.font = [UIFont systemFontOfSize:15];
35     _topLabel.textAlignment = NSTextAlignmentCenter;
36     _topLabel.text = @"文字顶部显示";
37     [self.view addSubview:_topLabel];
38     
39     _centerLabel = [[gzhVerticalAlignmentLabel alloc]initWithFrame:CGRectMake((ScreenW-200)/2.0, CGRectGetMaxY(_topLabel.frame)+10, 200, 80)];
40     _centerLabel.verticalAlignment = VerticalAlignmentMiddle;
41     _centerLabel.backgroundColor = [UIColor redColor];
42     _centerLabel.font = [UIFont systemFontOfSize:15];
43     _centerLabel.textAlignment = NSTextAlignmentCenter;
44     _centerLabel.text = @"文字中间显示";
45     [self.view addSubview:_centerLabel];
46     
47     
48     _bottomLabel = [[gzhVerticalAlignmentLabel alloc]initWithFrame:CGRectMake((ScreenW-200)/2.0, CGRectGetMaxY(_centerLabel.frame)+10, 200, 80)];
49     _bottomLabel.verticalAlignment = VerticalAlignmentBottom;
50     _bottomLabel.backgroundColor = [UIColor redColor];
51     _bottomLabel.font = [UIFont systemFontOfSize:15];
52     _bottomLabel.textAlignment = NSTextAlignmentCenter;
53     _bottomLabel.text = @"文字底部显示";
54     [self.view addSubview:_bottomLabel];
55 }
56 
57 
58 @end