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引言需求：（輸出框限制輸出多少字符）

1、一個字母、符號、數字相當於一個字符
2、一個漢字相當於兩個字符
3、不能輸出特殊字符
4、不能輸出emoji表情

直接上代碼 一、注冊告訴

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFieldChange:) name:UITextFieldTextDidChangeNotification object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFieldChange:) name:UITextViewTextDidChangeNotification object:nil];

二、告訴完成

- (void)textFieldChange:(UITextField *)textField
{
    //判別輸出(不能輸出特殊字符)
    [RestrictionInput restrictionInputTextField:self.titleTextField maxNumber:100 showView:self showErrorMessage:@"商品稱號0~100字符~"];

    [RestrictionInput restrictionInputTextView:self.infoTextView maxNumber:200 showView:self showErrorMessage:@"商品描繪0~200字符~"];

}

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    if ([RestrictionInput isInputRuleAndBlank:text] || [text isEqualToString:@""]) {//當輸出契合規則和退格鍵時允許改動輸出框
        return YES;
    } else {
        return NO;
    }
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if ([RestrictionInput isInputRuleAndBlank:string] || [string isEqualToString:@""]) {//當輸出契合規則和退格鍵時允許改動輸出框
        return YES;
    } else {
        return NO;
    }
}

三、封裝類（RestrictionInput）

.h

#import <Foundation/Foundation.h>

@interface RestrictionInput : NSObject

+ (void)restrictionInputTextField:(UITextField *)inputClass maxNumber:(NSInteger)maxNumber showView:(UIView *)showView showErrorMessage:(NSString *)errorMessage;

+ (void)restrictionInputTextView:(UITextView *)inputClass maxNumber:(NSInteger)maxNumber showView:(UIView *)showView showErrorMessage:(NSString *)errorMessage;

+ (BOOL)isInputRuleAndBlank:(NSString *)str;

.m

#import "RestrictionInput.h"

@implementation RestrictionInput

+ (void)restrictionInputTextField:(UITextField *)inputClass maxNumber:(NSInteger)maxNumber showView:(UIView *)showView showErrorMessage:(NSString *)errorMessage
{

    NSString *toBeString = inputClass.text;

    if (![self isInputRuleAndBlank:toBeString]) {
        inputClass.text = [self disable_emoji:toBeString];
        return;
    }

    NSString *lang = [[inputClass textInputMode] primaryLanguage]; // 獲取以後鍵盤輸出形式
    if([lang isEqualToString:@"zh-Hans"]) { //簡體中文輸出,第三方輸出法（搜狗）一切形式下都會顯示“zh-Hans”
        UITextRange *selectedRange = [inputClass markedTextRange];
        //獲取高亮局部
        UITextPosition *position = [inputClass positionFromPosition:selectedRange.start offset:0];
        //沒有高亮選擇的字，則對已輸出的文字停止字數統計和限制
        if(!position) {
            NSString *getStr = [self getSubString:toBeString maxNumber:maxNumber];
            if(getStr && getStr.length > 0) {
                inputClass.text = getStr;
                [showView showHudText:errorMessage hidedelay:1.0 completionBlock:nil];

                NSLog(@"%@", inputClass.text);
            }
        }
    } else{
        NSString *getStr = [self getSubString:toBeString maxNumber:maxNumber];
        if(getStr && getStr.length > 0) {
            inputClass.text= getStr;
            [showView showHudText:errorMessage hidedelay:1.0 completionBlock:nil];
            NSLog(@"%@",inputClass.text);
        }
    }
}

+ (void)restrictionInputTextView:(UITextView *)inputClass maxNumber:(NSInteger)maxNumber showView:(UIView *)showView showErrorMessage:(NSString *)errorMessage
{
    NSString *toBeString = inputClass.text;

    if (![self isInputRuleAndBlank:toBeString]) {
        inputClass.text = [self disable_emoji:toBeString];
        return;
    }

    NSString *lang = [[inputClass textInputMode] primaryLanguage]; // 獲取以後鍵盤輸出形式
    if([lang isEqualToString:@"zh-Hans"]) { //簡體中文輸出,第三方輸出法（搜狗）一切形式下都會顯示“zh-Hans”
        UITextRange *selectedRange = [inputClass markedTextRange];
        //獲取高亮局部
        UITextPosition *position = [inputClass positionFromPosition:selectedRange.start offset:0];
        //沒有高亮選擇的字，則對已輸出的文字停止字數統計和限制
        if(!position) {
            NSString *getStr = [self getSubString:toBeString maxNumber:maxNumber];
            if(getStr && getStr.length > 0) {
                inputClass.text = getStr;
                [showView showHudText:errorMessage hidedelay:1.0 completionBlock:nil];

                NSLog(@"%@", inputClass.text);
            }
        }
    } else{
        NSString *getStr = [self getSubString:toBeString maxNumber:maxNumber];
        if(getStr && getStr.length > 0) {
            inputClass.text= getStr;
            [showView showHudText:errorMessage hideDelay:1.0 completionBlock:nil];
            NSLog(@"%@",inputClass.text);
        }
    }
}

/**
 *  取得 kMaxLength長度的字符
 */
+ (NSString *)getSubString:(NSString*)string maxNumber:(NSInteger)maxNumber
{
    NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    NSData* data = [string dataUsingEncoding:encoding];
    NSInteger length = [data length];
    if (length > maxNumber) {
        NSData *data1 = [data subdataWithRange:NSMakeRange(0, maxNumber)];
        NSString *content = [[NSString alloc] initWithData:data1 encoding:encoding];//【留意4】：當截取kMaxLength長度字符時把中文字符截斷前往的content會是nil
        if (!content || content.length == 0) {
            data1 = [data subdataWithRange:NSMakeRange(0, maxNumber - 1)];
            content =  [[NSString alloc] initWithData:data1 encoding:encoding];
        }
        return content;
    }
    return nil;
}

/**
 * 字母、數字、中文正則判別（不包括空格）
 */
+ (BOOL)isInputRuleNotBlank:(NSString *)str {
    NSString *pattern = @"^[➋➌➍➎➏➐➑➒\a-zA-Z\u4E00-\u9FA5\\d]*$";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
    BOOL isMatch = [pred evaLuateWithObject:str];
    return isMatch;
}
/**
 * 字母、數字、中文正則判別（包括空格）【留意3】
 */
+ (BOOL)isInputRuleAndBlank:(NSString *)str {

    //九宮格無法輸出處理需求加上正則 \➋➌➍➎➏➐➑➒
    NSString *pattern = @"^[➋➌➍➎➏➐➑➒\a-zA-Z\u4E00-\u9FA5\\d\\s]*$";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
    BOOL isMatch = [pred evaLuateWithObject:str];
    return isMatch;
}

+ (NSString *)disable_emoji:(NSString *)text{
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"[^\\u0020-\\u007E\\u00A0-\\u00BE\\u2E80-\\uA4CF\\uF900-\\uFAFF\\uFE30-\\uFE4F\\uFF00-\\uFFEF\\u0080-\\u009F\\u2000-\\u201f\r\n]"options:NSRegularExpressionCaseInsensitive error:nil];
    NSString *modifiedString = [regex stringByReplacingMatchesInString:text
                                                               options:0
                                                                 range:NSMakeRange(0, [text length])
                                                          withTemplate:@""];
    return modifiedString;
}

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