给label绘制下划线

UIlabel本身没有下划线的属性，使用绘制的方法，添加下滑下，并且赋给该label一个action作为响应方法，实现DIY超链接的效果。

//调用

#import "UnderLineLabel.h"
 UnderLineLabel *label = [[UnderLineLabel alloc] initWithFrame:CGRectMake(, , , )];
    [label setBackgroundColor:[UIColor clearColor]];
    // [label setBackgroundColor:[UIColor yellowColor]];
    [label setTextColor:[UIColor blueColor]];
    [label setBackgroundColor:[UIColor yellowColor]];
    label.highlightedColor = [UIColor redColor];
    label.shouldUnderline = YES;

    [label setText:str andCenter:CGPointMake(, )];
    [label addTarget:self action:@selector(labelClicked)];
    [self.view addSubview:label];
  //  [label release];
//////"超链接执行的方法"
- (void)labelClicked
{
    NSLog(@"%@", NSStringFromSelector(_cmd));
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Clicked!" message:nil delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
    [alertView show];
    [alertView release];
}

UnderLineLabel.h

#import <UIKit/UIKit.h>

@interface UnderLineLabel : UILabel
{
    UIControl *_actionView;
    UIColor *_highlightedColor;
    BOOL _shouldUnderline;
}

@property (nonatomic, retain) UIColor *highlightedColor;
@property (nonatomic, assign) BOOL shouldUnderline;

- (void)setText:(NSString *)text andCenter:(CGPoint)center;
- (void)addTarget:(id)target action:(SEL)action;
@end
 

//  UnderLineLabel.m

//  UnderLineLabel.m

#import "UnderLineLabel.h"

@implementation UnderLineLabel
@synthesize highlightedColor = _highlightedColor;
@synthesize shouldUnderline = _shouldUnderline;

//- (void)dealloc
//{
//    [_actionView release],
//    _actionView = nil;
//    self.highlightedColor = nil;
//   [super dealloc];
//}

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
    }
    return self;
}

- (id)init
{
    if (self = [super init]) {
        self.font=[UIFont systemFontOfSize:];
    }
    return self;
}

- (id)initWithCoder:(NSCoder *)aDecoder
{
    if (self = [super initWithCoder:aDecoder]) {
    }
    return self;
}

- (void)setShouldUnderline:(BOOL)shouldUnderline
{
    _shouldUnderline = shouldUnderline;
    if (_shouldUnderline) {
        [self setup];
    }
}

- (void)drawRect:(CGRect)rect
{
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [super drawRect:rect];
    if (self.shouldUnderline) {
        NSLog(@"XXXXX");
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        CGSize fontSize =[self.text sizeWithFont:self.font
                                        forWidth:self.frame.size.width
                                   lineBreakMode:NSLineBreakByTruncatingTail];

        CGContextSetStrokeColorWithColor(ctx, self.textColor.CGColor);  // set as the text's color
        CGContextSetLineWidth(ctx, 2.0f);

        CGPoint leftPoint = CGPointMake(,
                                        self.frame.size.height);
        CGPoint rightPoint = CGPointMake(fontSize.width,
                                         self.frame.size.height);
        CGContextMoveToPoint(ctx, leftPoint.x, leftPoint.y);
        CGContextAddLineToPoint(ctx, rightPoint.x, rightPoint.y);
        CGContextStrokePath(ctx);
    }
}

- (void)setText:(NSString *)text andCenter:(CGPoint)center
{
    [super setText:text];
    CGSize fontSize =[self.text sizeWithFont:self.font
                                    forWidth:Phone_Weight-
                               lineBreakMode:NSLineBreakByTruncatingTail];
    NSLog(@"%f   %f", fontSize.width, fontSize.height);
    [self setNumberOfLines:];
    [self setFrame:CGRectMake(, , fontSize.width, fontSize.height)];
    [self setCenter:center];
}
- (void)setup
{
    [self setUserInteractionEnabled:TRUE];
    _actionView = [[UIControl alloc] initWithFrame:self.bounds];
    [_actionView setBackgroundColor:[UIColor clearColor]];
    [_actionView addTarget:self action:@selector(appendHighlightedColor) forControlEvents:UIControlEventTouchDown];
    [_actionView addTarget:self
                    action:@selector(removeHighlightedColor)
          forControlEvents:UIControlEventTouchCancel |
     UIControlEventTouchUpInside |
     UIControlEventTouchDragOutside |
     UIControlEventTouchUpOutside];
    [self addSubview:_actionView];
    [self sendSubviewToBack:_actionView];
}

- (void)addTarget:(id)target action:(SEL)action
{
    [_actionView addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
}

- (void)appendHighlightedColor
{
    self.backgroundColor = self.highlightedColor;
}

- (void)removeHighlightedColor
{
    self.backgroundColor = [UIColor clearColor];
}
@end