uitextfield动态限制输入的字数-b

1、定义一个事件：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

-(IBAction)limitLength:(UITextField *)sender {     bool isChinese;//判断当前输入法是否是中文     if ([[[UITextInputMode currentInputMode] primaryLanguage] isEqualToString: @"en-US"]) {         isChinese = false;     }     else     {         isChinese = true;     }           if(sender == self.txtName) {         // 8位         NSString *str = [[self.txtName text] stringByReplacingOccurrencesOfString:@"?" withString:@""];         if (isChinese) { //中文输入法下                 UITextRange *selectedRange = [self.txtName markedTextRange];                 //获取高亮部分                 UITextPosition *position = [self.txtName positionFromPosition:selectedRange.start offset:0];                 // 没有高亮选择的字，则对已输入的文字进行字数统计和限制                 if (!position) {                     NSLog(@"汉字");                     if ( str.length>=9) {                         NSString *strNew = [NSString stringWithString:str];                         [self.txtName setText:[strNew substringToIndex:8]];                     }                 }                 else                 {                     NSLog(@"输入的英文还没有转化为汉字的状态");                                   }         }else{             NSLog(@"str=%@; 本次长度=%d",str,[str length]);             if ([str length]>=9) {                 NSString *strNew = [NSString stringWithString:str];                 [self.txtName setText:[strNew substringToIndex:8]];             }         }     } }

2、对UITextField控件添加监听事件：

1 2	//UIControlEventEditingChanged [self.txtName addTarget:self action:@selector(limitLength:) forControlEvents:UIControlEventEditingChanged];