For a specialized calculator I would like to allow copy / paste for a textfield which is meant for numerical values only. So, only numerical characters should be actually pasted or the pasted string should be rejected if it contains non-numerical characters.
I was thinking about using UITextFieldDelegates textField:shouldChangeCharactersInRange:replacementString: method to check the pasted string for non-numerical characters. But NSString offers no method for checking whether it does NOT contain characters specified in a single set. So this way I would need to check occurances of characters from several sets, which is clumsy and these checks would run for every single number that would be typed in, which appears like quite some overhead to me.
Another way would be to iterate and check for every character in the replacement string whether there's a match in a numerical set.
Either way would propably work, but I feel like I'm missing something.
Do you have any advice? Is there a convenience method to achieve this?
But NSString offers no method for checking whether it does NOT contain characters specified in a single set
sure it does.
if([myString rangeOfCharacterFromSet:myCharacterSet].location ==NSNotFound)
{
//means there is no character from specified set in specified string
}
Related
As stated in the title, I have two tables I'm attempting to link. Both Strings appear to be a match, however Crystal Reports is not picking it up. The only thing I can think is that that length of the field is different, even though the strings are the same. could that cause a discrepancy? If so how can I correct for it? Thank you
Length of the string will prevent a match. If you are using the Trim(string) function, that only removes spaces found at the beginning or end of your string, so the two strings could still be of different lengths after using this function. You will need to use another function to capture a substring of the original string. To do this you can use the Left(string, length) function to ensure both strings are the same length.
If they still do not match then you may have non-printable characters in one or both of your strings. Carriage Return and Line Feed tend to be the most commonly found non-printable characters. A Carriage Return is represented as Chr(10), while a Line Feed is represented as Chr(13). These are Built In Constants similar to those found in VBA and Visual Basic.
You can use a find and replace to remove them with the following formula. Its not a bad idea to also include the trim and left functions in this as well to ensure you get the best match possible.
Replace(Replace(Left(Trim({YourStringField}), 10),Chr(10), ""),Chr(13), "")
There are a few additional Built In Constants you may need to check for if this doesn't work. A Tab is represented as Chr(9) for example. Its very rare for strings to contain the other Built In Constants though. In most cases Carriage Return and Line Feed are the only ones that are typically found in Plain Text. Tabs and the other constants should only be found in Rich Text and are very rare in string data.
I want to implement a class to read vorbis comments. I know that a field will start with a field name, followed by an equal sign and the value. But how does it end? Documentation makes me think that a semicolon will end the field but I checked an ogg file with a hex editor and I cannot see any.
This is how I think it should look like in a file :
TITLE=MY SUPER TITLE;
The field name is title, followed by the equals sign and then the value is MY SUPER TITLE. And finally the semicolon to end the field.
But instead inside my file, the fields look like this :
TITLE=MY SUPER TITLE....
It's almost as above but there is no semicolon. The .'s are characters that cannot be displayed. I thought okay, it seems like the dots represent a value that will say "this is the end of the field!!" but they are almost always different. I noticed that there are always exactly 4 dots. The first dot has always a different value. The other free have usually a value of 0. But not always...
My question now, how does a field end? How do I read this comment?
Also, yeah I know that there are libraries and that I should use them instead of reinventing the wheel over and over again. I will use libraries later but first I want to know how to do it myself. Educational purpose only.
Each field is preceded by a little-endian 32-bit integer that indicates the number of bytes to read. You then convert the bytes to a string via UTF8.
See NVorbis' implementation (LoadComments(...)) for details.
I want to use Unicode in my code. My Unicode value is 0100 and I am adding my Unicode string \u with my value. When I use string myVal="\u0100", it's working, but when I use like below, it's not working. The value is looking like "\\u1000";. How do I resolve this?
I want to use it like the below one, because the Unicode value may vary sometimes.
string uStr=#"\u" + "0100";
There are a couple of problems here. One is that #"\u" is actually the literal string "\u" (can also be represented as "\u").
The other issue is that you cannot construct a string in the way you describe because "\u" is not a valid string by itself. The compiler is expecting a value to follow "\u" (like "\u0100") to determine what the encoded value is supposed to be.
You need to keep in mind that strings in .NET are immutable, which means that when you look at what is going on behind the scenes with your concatenated example (`#"\u"+"0100"), this is what is actually happening:
Create the string "\u"
Create the string "0100"
Create the string "\u0100"
So you have three strings in memory. In order for that to happen all of the strings must be valid.
The first option that comes to mind for handling those values is to actually parse them as integers, and then convert them to characters. Something like:
var unicodeValue = (char)int.Parse("0100",System.Globalization.NumberStyles.AllowHexSpecifier);
Which will give you the single Unicode character value. From there, you can add it to a string, or convert it to a string using ToString().
In my current implementation of a UISearchBarController I'm using [NSString compare:] inside the filterContentForSearchText:scope: delegate method to return relevant objects based on their name property to the results UITableView as you start typing.
So far this works great in English and Korean, but what I'd like to be able to do is search within NSString's defined character clusters. This is only applicable for a handfull of languages, of which Korean is one.
In English, compare: returns new results after every letter you enter, but in Korean the results are generated once you complete a recognized grapheme cluster. I would like to be able to search through my Korean objects name property via the individual elements that make up a syllable.
Can anyone shed any light on how to approach this? I'm sure it has something to do with searching through UTF16 characters manually, or by utilising a lower level class.
Cheers!
Here is a specific example that's just not working:
`NSString *string1 = #"이";
`NSString *string2 = #"ㅣ";
NSRange resultRange = [[string1 decomposedStringWithCanonicalMapping] rangeOfString: [string2 decomposedStringWithCanonicalMapping] options:(NSLiteralSearch)];
The result is always NSNotFound, with or without decomposedStringWithCanonicalMapping.
Any ideas?
I'm no expert, but I think you're very unlikely to find a clean solution for what you want. There doesn't seem to be any relationship between a Korean character's Unicode value and the graphemes that it's made up of.
e.g. "이" is \uc774 and "ㅣ" is \u3163. From the perspective of the NSString, they're just two different characters with no specific relationship to each other.
I suspect that you will have to find or create an explicit mapping between characters and their graphemes, and then write your own search function that consults this mapping.
This very long page on Unicode Korean can help you, if it comes to that. It has a table of all the characters which suggests some structured relation between the way characters are numbered and their components.
If you use compare:options with NSLiteralString, it should compare character by character, that is, the Unicode code points, regardless of the grapheme. The default behavior of compare: is to use no options. You could use - decomposedStringWithCanonicalMapping to get the Unicode bytes of the input string, but I'm not sure how that would interact with compare:.
i have the following problem sometimes my openURL-Dialog works perfectly, then i looked at the variable from the url and that is the variable:
www.brehm-gmbh.de
but some other times there are some crazy elements at the end of the variable like this:
www.adamczyk-fenster.de%E2%80%8E
i get this pages from an .asc file and both are in this file normal without this elements,
what can i do to solve this problem?
thank you all for helping beforehand
From Wikipedia:
The left-to-right mark (LRM) is a
control character or non-printing
character, used in the computerized
typesetting of bi-directional text,
containing mixed left-to-right scripts
(such as English and Russian) and
right-to-left scripts (such as Arabic
and Hebrew). It is used to change the
way adjacent characters are grouped
with respect to text direction.
You're getting this because (1) you've got non-English URLs, are composing URLs from non-English strings or you have some other non-English elements and the string encoding is attempting to compensate or (2) it's garbarge being interpreted as an encoding (unlikely if it is consistant.)
Call -[NSString localizedNameOfStringEncoding] on the string before you use it see what encoding it is using. You probably need to explicitly establish an encoding when you read in the strings before you put them in the NSURL.