最近項目需求，要實現一個類似微信的的表情輸入，於是把微信的表情扒拉出來，實現了一把。可以從這裡下載源碼。看起來表情輸入沒有多少東西，不外乎就是用NSTextAttachment來實現圖文混排，結果在實現的過程中遇到了很多小問題，接下來會一一介紹遇到過的坑。先上一張效果圖：

一、實現表情選擇View(WKExpressionView)

具體的實現就不細說了，主要功能就是點擊表情時，將對應表情的圖片名稱通知給delegate。

二、實現表情textView(WKExpressionTextView)

WKExpressionTextView繼承自UITextView, 提供
- (void)setExpressionWithImageName:(NSString *)imageName fontSize:(CGFloat)fontSize方法，用於根據圖片插入表情。 具體實現：

//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];
//在當前編輯位置插入字符串
[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繼承自NSTextAttachment, 並新增text字段，為了保存表情對應的文本，用於復制粘貼操作。

@interface WKExpressionTextAttachment : NSTextAttachment
@property (nonatomic, copy) NSString *text;
@end

WKExpressionTool的提供將普通字符串轉換為富文本的方法，主要用於復制時生成表情。

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;
}

/**
* 通過表情生成富文本
*
* @param expressionString 表情名
* @param fontSize 對應字體大小
*
* @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，基本功能實現完成。 接下來說說遇到的小問題

編輯是應該對應selectedRange

復制粘貼操作需要重新實現

textView在插入NSTextAttachment後，會默認把font的size修改為12，需要記錄默認的size

對應selectedRange操作

具體的操作查看源碼

重新實現copy、cut方法

進行復制、粘貼操作會發現，不能對圖片進行復制，所以需要自己重寫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];
}

記錄默認font的size

利用實例變量defaultFontSize，在WKExpressionTextView實例化時記錄self.font.pointSize，以後需要取font的size時，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;
}

以上所述是小編給大家介紹的iOS高仿微信表情輸入功能代碼分享，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對本站網站的支持！