參考文獻(xiàn):http://www.reibang.com/p/ea6b8c026f6b

#import "ViewController.h"

#define kMaxLength 20



@interface ViewController ()<UITextFieldDelegate>

@property (weak, nonatomic) IBOutlet UITextField *demoTextField;

@end

@implementation ViewController





- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self.demoTextField addTarget:self action:@selector(textFieldChanged:) forControlEvents:UIControlEventEditingChanged];
    self.demoTextField.delegate = self;
}




- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    
    NSLog(@"------------shouldChangeCharactersInRange:%@-----------",string);
    
    if ([self isInputRuleNotBlank:string] || [string isEqualToString:@""]) {//當(dāng)輸入符合規(guī)則和退格鍵時(shí)允許改變輸入框
        return YES;
    } else {
        return NO;
    }
}



- (void)textFieldChanged:(UITextField *)textField {
    
    NSLog(@"----------textFieldChanged:%@-------------",textField.text);
    
    NSString *toBeString = textField.text;
    
    if (![self isInputRuleAndBlank:toBeString]) {
        
        textField.text = [self disable_emoji:toBeString];
        return;
    }
   
    NSString *lang = [[textField textInputMode] primaryLanguage]; // 獲取當(dāng)前鍵盤(pán)輸入模式
    
    
    NSLog(@"%@",lang);
    
    
    
    if([lang isEqualToString:@"zh-Hans"])
    { //簡(jiǎn)體中文輸入,第三方輸入法（搜狗）所有模式下都會(huì)顯示“zh-Hans”
        UITextRange *selectedRange = [textField markedTextRange];
        //獲取高亮部分
        UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
        //沒(méi)有高亮選擇的字，則對(duì)已輸入的文字進(jìn)行字?jǐn)?shù)統(tǒng)計(jì)和限制
        if(!position) {
            NSString *getStr = [self getSubString:toBeString];
            if(getStr && getStr.length > 0) {
                textField.text = getStr;
            }
        }
    }
    else
    {
         NSString *getStr = [self getSubString:toBeString];
        if(getStr && getStr.length > 0) {
            textField.text= getStr;
        }
    }
    
    
}














/**
 * 字母、數(shù)字、中文正則判斷（不包括空格）
 */
- (BOOL)isInputRuleNotBlank:(NSString *)str {

    //NSString *pattern = @"^[a-zA-Z\u4E00-\u9FA5\\d]*$";
    NSString *pattern = @"^[????????a-zA-Z\u4E00-\u9FA5\\d]*$";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
    BOOL isMatch = [pred evaluateWithObject:str];
    return isMatch;
}




/**
 * 字母搀愧、數(shù)字该镣、中文正則判斷（包括空格）（在系統(tǒng)輸入法中文輸入時(shí)會(huì)出現(xiàn)拼音之間有空格荆姆，需要忽略攻询，當(dāng)按return鍵時(shí)會(huì)自動(dòng)用字母替換恶复，按空格輸入響應(yīng)漢字）
 */
- (BOOL)isInputRuleAndBlank:(NSString *)str {
    
    //NSString *pattern = @"^[a-zA-Z\u4E00-\u9FA5\\d\\s]*$";
    NSString *pattern = @"^[????????a-zA-Z\u4E00-\u9FA5\\d\\s]*$";
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
    BOOL isMatch = [pred evaluateWithObject:str];
    return isMatch;
}











/**
 *  獲得 kMaxLength長(zhǎng)度的字符
 */
-(NSString *)getSubString:(NSString*)string
{
    NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    NSData* data = [string dataUsingEncoding:encoding];
    NSInteger length = [data length];
    if (length > kMaxLength) {
        NSData *data1 = [data subdataWithRange:NSMakeRange(0, kMaxLength)];
        NSString *content = [[NSString alloc] initWithData:data1 encoding:encoding];//注意：當(dāng)截取kMaxLength長(zhǎng)度字符時(shí)把中文字符截?cái)喾祷氐腸ontent會(huì)是nil
        if (!content || content.length == 0) {
            data1 = [data subdataWithRange:NSMakeRange(0, kMaxLength - 1)];
            content =  [[NSString alloc] initWithData:data1 encoding:encoding];
        }
        return content;
    }
    return nil;
}




- (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;
}






- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self.view endEditing:YES];
}