仿微信表情输入

哇哦，好久没有写过博客了，前段时间太忙了。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-Z0-9\u4e00-\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;

}

至此，基本功能实现完成。 接下来说说遇到的小问题

编辑是应该对应selectedRange

复制粘贴操作需要重新实现

textView在插入NSTextAttachment后，会默认把font的size修改为12，需要记录默认的size


具体的操作查看源码


进行复制、粘贴操作会发现，不能对图片进行复制，所以需要自己重写copy、cut方法

- (void)copy:(id)sender
{
NSAttributedString *selectedString = [self.attributedText attributedSubstringFromRange:self.selectedRange];
NSString *copyString = [self parseAttributeTextToNormalString:selectedString];

UIPasteboard *pboard = [UIPasteboard generalPasteboard];
if (copyString.length != 0) {
pboard.string = copyString;
}
}

- (void)cut:(id)sender
{
[self copy:sender];

NSMutableAttributedString *originalString = [[NSMutableAttributedString alloc] initWithAttributedString:self.attributedText];
[originalString deleteCharactersInRange:self.selectedRange];
self.attributedText = originalString;

NSLog(@"--%@", NSStringFromRange(self.selectedRange));
[self textChanged];
}

利用实例变量defaultFontSize，在WKExpressionTextView实例化时记录self.font.pointSize，以后需要取font的size时，直接取defaultFontSize

@interface WKExpressionTextView : UITextView

@property (nonatomic, assign) CGFloat defaultFontSize;

@end

@implementation WKExpressionTextView

{
CGFloat _defaultFontSize;
}

- (void)awakeFromNib
{
[self setup];
}

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

- (void)setup
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChange:) name:UITextViewTextDidChangeNotification object:self];

_defaultFontSize = self.font.pointSize;

self.delegate = self;
}