cdts/xdts-ios 3/TreeHole/Code/Utility/TextInputLimit/NSString+MTLimit.m

//
//  NSString+MTLimit.m
//  Meet
//
//  Created by ko1o on 2018/10/22.
//  Copyright © 2018年 ko1o. All rights reserved.
//

#import "NSString+MTLimit.h"

@implementation NSString (MTLimit)

- (NSInteger)mt_customByteLength
{
    //拿到所有str的length长度（包括中文英文..都算为1个字符）
    NSUInteger len = self.length;
    //汉字字符集
    //    NSString* pattern = @"[\u4e00-\u9fa5]";
    //    NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern:pattern options:NSRegularExpressionCaseInsensitive error:nil];
    //    //计算中文字符的个数
    //    NSInteger numMatch = [regex numberOfMatchesInString:self options:NSMatchingReportProgress range:NSMakeRange(0, len)];
    //    //计算中文2个字符，英文1个字符
    //    return len + numMatch;
    //两个英文字符算1个长度,中文的话默认也是1,emoj表情返回是不固定的长度 2-7
    static NSRegularExpression* regex;
    if (!regex) {
        NSString* pattern = @"[a-zA-Z]";
        regex = [NSRegularExpression regularExpressionWithPattern:pattern options:NSRegularExpressionCaseInsensitive error:nil];
    }
    NSInteger numMatch = [regex numberOfMatchesInString:self options:NSMatchingReportProgress range:NSMakeRange(0, len)];
    return len - (numMatch ) / 2;
}

- (NSString *)mt_safeSubStringWithStringLength:(NSInteger)maxLength
{
    return [self mt_safeSubStringWithByteLength:maxLength isCaculateCustomByteLength:NO];
}

- (NSString *)mt_safeSubStringWithByteLength:(NSInteger)maxLength
{
    return [self mt_safeSubStringWithByteLength:maxLength isCaculateCustomByteLength:YES];
}

- (NSString *)mt_safeSubStringWithByteLength:(NSInteger)maxLength isCaculateCustomByteLength:(BOOL)isCaculateCustomByteLength
{
    NSString * textString = self;
    NSRange fullRange = NSMakeRange(0, [textString length]);
    __block NSMutableString * resultString = [NSMutableString string];
    NSInteger currentLength = isCaculateCustomByteLength ? textString.mt_customByteLength :textString.length;
    
    if (currentLength > maxLength) {
        [textString enumerateSubstringsInRange:fullRange
                                       options:NSStringEnumerationByComposedCharacterSequences
                                    usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop)
         {
             //         NSLog(@"%@ %@", substring, NSStringFromRange(substringRange));
             NSMutableString * toString = [resultString mutableCopy];
             [toString appendString:substring];
             
             NSInteger currentLength = isCaculateCustomByteLength ? toString.mt_customByteLength :toString.length;
             if (currentLength <= maxLength) {
                 resultString = toString;
             } else {
                 *stop = YES;
             }
         }];
        textString = [resultString copy];
    }
    return textString;
}

//判断字符串的字符个数 Unicode编码后是按4个字符算的
- (NSInteger)mt_unicodeCharacterByteLength
{
    NSString * tempStr = self;
    int strlength = 0;
    char* p = (char*)[tempStr cStringUsingEncoding:NSUnicodeStringEncoding];
    for (int i=0 ; i<[tempStr lengthOfBytesUsingEncoding:NSUnicodeStringEncoding] ;i++) {
        if (*p) {
            p++;
            strlength++;
        }
        else {
            p++;
        }
        
    }
    return strlength;
}

- (BOOL)mt_stringContainsEmoji
{
    // 过滤所有表情。returnValue为NO表示不含有表情，YES表示含有表情
    __block BOOL returnValue = NO;
    [self enumerateSubstringsInRange:NSMakeRange(0, [self length]) options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
        
        const unichar hs = [substring characterAtIndex:0];
        // surrogate pair
        if (0xd800 <= hs && hs <= 0xdbff) {
            if (substring.length > 1) {
                const unichar ls = [substring characterAtIndex:1];
                const int uc = ((hs - 0xd800) * 0x400) + (ls - 0xdc00) + 0x10000;
                if (0x1d000 <= uc && uc <= 0x1f77f) {
                    returnValue = YES;
                }
            }
        } else if (substring.length > 1) {
            const unichar ls = [substring characterAtIndex:1];
            if (ls == 0x20e3) {
                returnValue = YES;
            }
        } else {
            // non surrogate
            if (0x2100 <= hs && hs <= 0x27ff) {
                returnValue = YES;
            } else if (0x2B05 <= hs && hs <= 0x2b07) {
                returnValue = YES;
            } else if (0x2934 <= hs && hs <= 0x2935) {
                returnValue = YES;
            } else if (0x3297 <= hs && hs <= 0x3299) {
                returnValue = YES;
            } else if (hs == 0xa9 || hs == 0xae || hs == 0x303d || hs == 0x3030 || hs == 0x2b55 || hs == 0x2b1c || hs == 0x2b1b || hs == 0x2b50) {
                returnValue = YES;
            }
        }
    }];
    return returnValue;
}

@end