最近项目需求，要实现一个类似微信的的表情输入，于是把微信的表情扒拉出来，实现了一把。可以从这里下载源码。看起来表情输入没有多少东西，不外乎就是用NSTextAttachment来实现图文混排，结果在实现的过程中遇到了很多小问题，接下来会一一介绍遇到过的坑。先上一张效果图：
一、实现表情选择View(WKExpressionView)
具体的实现就不细说了，主要功能就是点击表情时，将对应表情的图片名称通知给delegate。
二、实现表情textView(WKExpressionTextView)
WKExpressionTextView继承自UITextView, 提供
- (void)setExpressionWithImageName:(NSString *)imageName fontSize:(CGFloat)fontSize方法，用于根据图片插入表情。 具体实现：
//富文本
WKExpressionTextAttachment *attachment = [[WKExpressionTextAttachment alloc] initWithData:nil ofType:nil];
UIImage *image = [UIImage imageNamed:imageName];
attachment.image = image;
attachment.text = [WKExpressionTool getExpressionStringWithImageName:imageName];
attachment.bounds = CGRectMake(0, 0, fontSize, fontSize);
NSAttributedString *insertAttributeStr = [NSAttributedString attributedStringWithAttachment:attachment];
NSMutableAttributedString *resultAttrString = [[NSMutableAttributedString alloc] initWithAttributedString:self.attributedText];
//在当前编辑位置插入字符串
[resultAttrString insertAttributedString:insertAttributeStr atIndex:self.selectedRange.location];
NSRange tempRange = self.selectedRange;
self.attributedText = resultAttrString;
self.selectedRange = NSMakeRange(tempRange.location + 1, 0);
[self.textStorage addAttributes:@{NSFontAttributeName : [UIFont systemFontOfSize:_defaultFontSize]} range:NSMakeRange(0, self.attributedText.length)];
[self scrollRangeToVisible:self.selectedRange];
[self textChanged];
其中WKExpressionTextAttachment继承自NSTextAttachment, 并新增text字段，为了保存表情对应的文本，用于复制粘贴操作。
@interface WKExpressionTextAttachment : NSTextAttachment
@property (nonatomic, copy) NSString *text;
@end
WKExpressionTool的提供将普通字符串转换为富文本的方法，主要用于复制时生成表情。
主要方法
+ (NSAttributedString *)generateAttributeStringWithOriginalString:(NSString *)originalString fontSize:(CGFloat)fontSize
{
NSError *error = NULL;
NSMutableAttributedString *resultAttrString = [[NSMutableAttributedString alloc] initWithString:originalString];
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"[[a-zA-Z0-9u4e00-u9fa5]{1,}]" options:NSRegularExpressionAllowCommentsAndWhitespace error:&error];
NSArray *results = [regex matchesInString:originalString options:NSMatchingReportCompletion range:NSMakeRange(0, originalString.length)];
if (results) {
for (NSTextCheckingResult *result in results.reverseObjectEnumerator) {
NSRange resultRange = [result rangeAtIndex:0];
NSString *stringResult = [originalString substringWithRange:resultRange];
NSLog(@"%s %@n", __FUNCTION__, stringResult);
NSAttributedString *expressionAttrString = [self getAttributeStringWithExpressionString:stringResult fontSize:fontSize];
[resultAttrString replaceCharactersInRange:resultRange withAttributedString:expressionAttrString];
}
}
return resultAttrString;
}
/**
* 通过表情生成富文本
*
* @param expressionString 表情名
* @param fontSize 对应字体大小
*
* @return 富文本
*/
+ (NSAttributedString *)getAttributeStringWithExpressionString:(NSString *)expressionString fontSize:(CGFloat)fontSize
{
NSString *imageName = [self getExpressionStringWithImageName:expressionString];
WKExpressionTextAttachment *attachment = [[WKExpressionTextAttachment alloc] initWithData:nil ofType:nil];
UIImage *image = [UIImage imageNamed:imageName];
attachment.image = image;
attachment.text = [WKExpressionTool getExpressionStringWithImageName:imageName];
attachment.bounds = CGRectMake(0, 0, fontSize, fontSize);
NSAttributedString *appendAttributeStr = [NSAttributedString attributedStringWithAttachment:attachment];
return appendAttributeStr;
}
