如何让textField输入框 限制输入字数的同时，还只让输入数字和字母

1.  实现

UITextFieldDelegate  协议。

2.  在头文件中，定义如下变量：

//最多的账户字符个数

#define ACCOUNT_MAX_CHARS 16

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3. 在实现文件中：

将 textFiled对象的delegate设置为self:

m_accountField = [[UITextField alloc] initWithFrame:CGRectMake(89,26, 243, 33)];

m_accountField.borderStyle = UITextBorderStyleNone;

m_accountField.font = fieldFont;

m_accountField.delegate = self;

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//UITextFieldDelegate

- (BOOL)textFieldShouldReturn:(UITextField *)textField;

{

//用户结束输入

[textField resignFirstResponder];

return YES;

}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string // return NO to not change text

{

//判断是否超过 ACCOUNT_MAX_CHARS 个字符,注意要判断当string.leng>0

//的情况才行，如果是删除的时候，string.length==0

int length = textField.text.length;

if (length >= ACCOUNT_MAX_CHARS && string.length >0)

{

return NO;

}

NSCharacterSet *cs;

cs = [[NSCharacterSet characterSetWithCharactersInString:kAlphaNum] invertedSet];

NSString *filtered =

[[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];

BOOL basic = [string isEqualToString:filtered];

return basic;

}

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原文链接：http://blog.csdn.net/tangaowen/article/details/8087798