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