UITextField监听金额的输入

#pragma mark - UITextFieldDelegate

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

    NSString * toBeString = [textField.text stringByReplacingCharactersInRange:range withString:string];    if([toBeString containsString:@"."]) {      

   kMaxLength=8;

    }else{

kMaxLength=5;    }

    UITextRange*selectedRange = [textField markedTextRange];    //获取高亮部分

   UITextPosition*position = [textField positionFromPosition:selectedRange.startoffset: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) {

        if(toBeString.length>kMaxLength&& range.length!=1){

            textField.text= [toBeString  substringToIndex:kMaxLength];

            returnNO;

        }

    }    // 有高亮选择的字符串，则暂不对文字进行统计和限制

  else{}

    if(string.length==0) {

        returnYES;    }

return [NSString isValid:toBeString];

    return YES;

}