iPhone开发：类似iChat的聊天泡泡示例

很多iPhone聊天程序消息显示都喜欢做成iChat的泡泡样式，这样是不是很apple呢？

那么下面用一种简单的方法来实现它。

主要通过

UIlabel的sizeToFit方法自动计算文本区域大小

UIImage的- (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight;方法拉伸图片

可以根据文本内容自动适应算泡泡高度

- (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight;的含义是

横向从leftCapWidth+1个像素开始，该像素被横向无限复制，作为中间部分，剩余部分又被链接到一起组成整张图

纵向从topCapHeight+1个像素开始，该像素被纵向无限复制，作为中间部分，剩余部分又被链接到一起组成整张图

所有拉伸后的图片不会变模糊。

效果如下，先上图

所要用到的资源

和

定义一个类ChatPopView，代码日下

#import <UIKit/UIKit.h>

typedef enum tagPopDirection

{

ePopDirectionLeft = 0,

ePopDirectionRight

}ePopDirection;

@interface ChatPopView : UIView {

UIImageView *popBackground;

UILabel     *contentLabel;

ePopDirection direction;

}

@property (nonatomic,retain) UIImageView *popBackground;

@property (nonatomic,retain) UILabel     *contentLabel;

@property (assign) ePopDirection direction;

-(id)initWithFrame:(CGRect)frame popDirection:(ePopDirection) d;

-(void)setText:(NSString *)str;

@end

#import "ChatPopView.h"

@implementation ChatPopView

@synthesize popBackground;

@synthesize contentLabel;

@synthesize direction;

-(id)initWithFrame:(CGRect)frame popDirection:(ePopDirection) d{

self = [super initWithFrame:frame];

if (self) {

self.backgroundColor = [UIColor clearColor];

self.direction = d;

UIImageView *back = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];

self.popBackground = back;

[back release];

UIImage *theImage = nil;

if (ePopDirectionRight== self.direction) {

theImage = [UIImage imageNamed:@"SSMessageTableViewCellBackgroundGreen"];

}else {

theImage = [UIImage imageNamed:@"SSMessageTableViewCellBackgroundClear"];

}

popBackground.image = [theImage stretchableImageWithLeftCapWidth:21 topCapHeight:15];

[self addSubview:popBackground];

UILabel *content = [[UILabel alloc] initWithFrame:CGRectMake(15, 5, frame.size.width - 15, frame.size.height)];

self.contentLabel = content;

[content release];

contentLabel.numberOfLines = 0;

contentLabel.backgroundColor = [UIColor clearColor];

[self addSubview:contentLabel];

}

return self;

}

-(void)setText:(NSString *)str{

contentLabel.text = str;

[contentLabel sizeToFit];

[self setNeedsLayout];

}

-(void)layoutSubviews{

[super layoutSubviews];

self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, contentLabel.frame.size.width+30, contentLabel.frame.size.height+15);

popBackground.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);

}

- (void)dealloc {

[popBackground release];

[contentLabel release];

    [super dealloc];

}

我们可以这样使用

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

    

    // Override point for customization after application launch.

    

    [self.window makeKeyAndVisible];

ChatPopView *pop1 = [[ChatPopView alloc] initWithFrame:CGRectMake(20, 100, 200, 80) popDirection:ePopDirectionLeft];

[self.window addSubview:pop1];

[pop1 setText:@"Sent when the application is about to move from active to inactive state. "];

ChatPopView *pop2 = [[ChatPopView alloc] initWithFrame:CGRectMake(130, 220, 200, 40) popDirection:ePopDirectionRight];

[self.window addSubview:pop2];

[pop2 setText:@"This can occur for certain types of..."];

ChatPopView *pop3 = [[ChatPopView alloc] initWithFrame:CGRectMake(20, 300, 280, 300) popDirection:ePopDirectionLeft];

[self.window addSubview:pop3];

[pop3 setText:@""];

ChatPopView *pop4 = [[ChatPopView alloc] initWithFrame:CGRectMake(230, 400, 200, 40) popDirection:ePopDirectionRight];

[self.window addSubview:pop4];

[pop4 setText:@""];

[pop1 release];

    return YES;

}