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:@"\[[a-zA-Z0-9u4e00-u9fa5]{1,}\]" 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 %@
", __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

对应selectedRange操作

具体的操作查看源码

重新实现copy、cut方法

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];
}

记录默认font的size

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;
}