学步园

在IOS实际开发中有些UITextField需要限制输入内容，如账号、密码等，下面简单介绍其简单的实现方法，如下：

//定义宏（限制输入内容）

#define kAlphaNum  @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"

#define kAlpha      @"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
"

#define kNumbers     @"0123456789"

#define kNumbersPeriod  @"0123456789."

//定义UITextFiled的代理方法：

- (BOOL)textField:(UITextField *)textField

    shouldChangeCharactersInRange:(NSRange)range

    replacementString:(NSString *)string
{

    NSCharacterSet *cs;

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

    NSString *filtered
=

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

    BOOL basic
= [string isEqualToString:filtered];

    return basic;

}