iOS高仿微信表情输入功能代码分享

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

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;
}

以上所述是小编给大家介绍的iOS高仿微信表情输入功能代码分享，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！