UILabel 详解

UILabel 多行文字自动换行 （自动折行）

1.UIView *footerView = [[UIView alloc] initWithFrame:CGRectMake(10, 100, 300, 180)];   
2.    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 100, 300, 150)];   
3.    label.text = @"where are you? where are you? where are you? where are you? where are you? where are you? where are you? where are you? where are you? where are you?";   
4.    //清空背景颜色   
5.    label.backgroundColor = [UIColor clearColor];   
6.    //设置字体颜色为白色   
7.    label.textColor = [UIColor whiteColor];   
8.    //文字居中显示   
9.    label.textAlignment = UITextAlignmentCenter;   
10.    //自动折行设置   
11.    label.lineBreakMode = UILineBreakModeWordWrap;   
12.    label.numberOfLines = 0;

​​iOS的UILabel设置居上对齐，居中对齐，居下对齐​​

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：

[cpp] ​​view plain​​​​copy​​

1. 1. 
      
2. //
3. // myUILabel.h
4. //
5. //
6. // Created by yexiaozi_007 on 3/4/13.
7. // Copyright (c) 2013 yexiaozi_007. All rights reserved.
8. //
9. 
   
10. #import <UIKit/UIKit.h>
11. typedef enum
12. {
13. VerticalAlignmentTop = 0, // default
14. VerticalAlignmentMiddle,
15. VerticalAlignmentBottom,
16. } VerticalAlignment;
17. @interface myUILabel : UILabel
18. {
19. @private
20. VerticalAlignment _verticalAlignment;
21. }
22. 
    
23. @property (nonatomic) VerticalAlignment verticalAlignment;
24. 
    
25. @end
    1. 
       

[cpp] ​​view plain​​​​copy​​

1. 1. 
      
2. //
3. // myUILabel.m
4. //
5. //
6. // Created by yexiaozi_007 on 3/4/13.
7. // Copyright (c) 2013 yexiaozi_007. All rights reserved.
8. //
9. 
   
10. #import "myUILabel.h"
11. 
    
12. @implementation myUILabel
13. @synthesize verticalAlignment = verticalAlignment_;
14. 
    
15. - (id)initWithFrame:(CGRect)frame {
16. if (self = [super initWithFrame:frame]) {
17. self.verticalAlignment = VerticalAlignmentMiddle;
18. }
19. return self;
20. }
21. 
    
22. - (void)setVerticalAlignment:(VerticalAlignment)verticalAlignment {
23. verticalAlignment_ = verticalAlignment;
24. [self setNeedsDisplay];
25. }
26. 
    
27. - (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines {
28. CGRect textRect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];
29. switch (self.verticalAlignment) {
30. case VerticalAlignmentTop:
31. textRect.origin.y = bounds.origin.y;
32. break;
33. case VerticalAlignmentBottom:
34. textRect.origin.y = bounds.origin.y + bounds.size.height - textRect.size.height;
35. break;
36. case VerticalAlignmentMiddle:
37. // Fall through.
38. default:
39. textRect.origin.y = bounds.origin.y + (bounds.size.height - textRect.size.height) / 2.0;
40. }
41. return textRect;
42. }
43. 
    
44. -(void)drawTextInRect:(CGRect)requestedRect {
45. CGRect actualRect = [self textRectForBounds:requestedRect limitedToNumberOfLines:self.numberOfLines];
46. [super drawTextInRect:actualRect];
47. }
48. 
    
49. 
    
50. @end
    1. 
       

在使用时：

[cpp] ​​view plain​​​​copy​​

1. 1. 1. 
         
   2. lbl_mylabel = [[myUILabel alloc] initWithFrame:CGRectMake(20, 50, 150, 600)];
   3. UIColor *color = [UIColor colorWithPatternImage:[UIImage imageNamed:@"halfTransparent.png"]];//使用半透明图片作为label的背景色
   4. lbl_mylabel.backgroundColor = color;
   5. lbl_mylabel.textAlignment = UITextAlignmentLeft;
   6. lbl_mylabel.textColor = UIColor.whiteColor;
   7. lbl_mylabel.lineBreakMode = UILineBreakModeWordWrap;
   8. lbl_mylabel.numberOfLines = 0;
   9. [lbl_mylabel setVerticalAlignment:VerticalAlignmentTop];
   10. [self addSubview:lbl_mylabel];
       1. 
          

ios UILabel 变量名不能为title

-[UILabel copyWithZone:]: unrecognized selector sent to instance

遇到了这样一个错误，找了半天没找到是什么错误，于是，Google搜索，打开第一个链接http://stackoverflow.com/questions/10784207/uilabel-copywithzone-unrecognized-selector-sent-to-instance UILabel 设置过长文本中间为省略号

label.lineBreakMode = NSLineBreakByTruncatingMiddle;