限制UITextField只接收数字输入

1、定义宏
#define NUMBERS @"0123456789\n"
2、实现
UITextFieldDelegate的
- (BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string；方法。

- (BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSCharacterSet* filterCS = [[NSCharacterSet
characterSetWithCharactersInString:NUMBERS]
invertedSet];
NSString* filterString = [[string
componentsSeparatedByCharactersInSet:filterCS] componentsJoinedByString:@""];
BOOL flag = [string isEqualToString:filterString];
if (!flag)
{
UIAlertView* alert = [[UIAlertView
alloc] initWithTitle:@"提示"
message:@"请输入数字" delegate:nil
cancelButtonTitle:@"确定" otherButtonTitles:
nil];
[alert show];
[alert release];

return NO;
}

return YES;
}