iOS textField文字输入字数以及格式限制

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

NSInteger existedLength = textField.text.length;

NSInteger selectedLength = range.length;

NSInteger replaceLength = string.length;

if (existedLength - selectedLength + replaceLength < 7) {

if ([string length]>0)

{

unichar single=[string characterAtIndex:0];//当前输入的字符

if ((single >=‘0‘ && single<=‘9‘))//数据格式正确

{

return YES;

}else{

return NO;

}

}else{

return YES;

}

}else{

return NO;

}

}