实用知识：正则表达式表情匹配

另一种思路：在最后一个位置开始往前替换更改图片

#import "ViewController.h"#import "NSString+RegularExpression.h"#import "ZTextAttachment.h"@interface ViewController ()@property (weak, nonatomic) IBOutlet UILabel *label;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    self.label.text = @"[smiley_29]召召, 你的肥皂[smiley_2]丢了吗?[smiley_6]";}- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    /*================= 将文字替换成表情 =================*/    NSString *content = self.label.text;    // 1. 查找符合条件的文本 , 正则    // \[\w+\]    由于[]在正则中是特殊语法, 因此使用 \[ 和 \] 来表示普通的[或]文本    NSString *pattern = @"\\[\\w+\\]";    // [图片名] 在 整句话当中的Range    NSArray <NSValue *> *rangeArray = [content matchesRangeWithPattern:pattern];    // content的富文本 (原始的)    NSMutableAttributedString *attrContent = [[NSMutableAttributedString alloc] initWithString:content];    // 对每一个文字进行替换    // lengthChanged 来记录 富文本替换表情后长度的变化    NSUInteger totalLengthChanged = 0;    for (NSValue *value in rangeArray) {        /*================= Content - NSString =================*/        // [smiley_29]召召, 你的肥皂[smiley_2]丢了吗?[smiley_6]        // 1. 获取图片        NSRange range = value.rangeValue;        NSString *imagename = [content substringWithRange:NSMakeRange(range.location + 1, range.length -2)];        UIImage *image = [UIImage imageNamed:imagename];        // 2. 创建对应图片的富文本, 长度为1        ZTextAttachment *attachment = [[ZTextAttachment alloc] init];        attachment.image = image;        NSAttributedString *imageAttrString = [NSAttributedString attributedStringWithAttachment:attachment];        /*================= AttrContent - NSTextAttributeString =================*/        // (表情)召召, 你的肥皂[smiley_2]丢了吗?[smiley_6]        NSUInteger originalLength = attrContent.length;    // 改变前长度        // 计算前的Range值        NSRange newRange = NSMakeRange(range.location - totalLengthChanged, range.length);        [attrContent replaceCharactersInRange:newRange withAttributedString:imageAttrString];        NSUInteger finalLength = attrContent.length;    // 改变后的长度        NSUInteger lengthChanged = originalLength - finalLength;    // 这一次图片替换长度的改变        totalLengthChanged += lengthChanged;    // 累加每一次的改变    }    [self.label setAttributedText:attrContent];}@end

#import <UIKit/UIKit.h>@interface ZTextAttachment : NSTextAttachment@end#import "ZTextAttachment.h"@implementation ZTextAttachment// 返回附件(例子是图片)的Bounds- (CGRect)attachmentBoundsForTextContainer:(NSTextContainer *)textContainer proposedLineFragment:(CGRect)lineFrag glyphPosition:(CGPoint)position characterIndex:(NSUInteger)charIndex{    // lineFrag 代表附近所在的文字所占的Rect值    return CGRectMake(0, -lineFrag.size.height * 0.2, lineFrag.size.height, lineFrag.size.height);}@end