Hey! I was wondering if there was any way to check if the first letter of a string was capital or not in an NSString. Something similar to:
if ([[string substringToIndex:1] isCapitalLetter]) {
// CODE
}
--or--
if ([self isCapitalLetter:[string substringToIndex:1]]) {
// CODE
}
[[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[myString characterAtIndex:0]];
The only thing I can think of would be to do something like this:
// get the first character, capitalized
NSString *capital = [[oldstring substringToIndex:1] capitalizedString];
// then compare to your oldstring
if ( [[oldstring substringToIndex:1] isEqualToString:capital] ) {
// do stuff...
}
The NSString reference is your friend: http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html
Related
I'm new with iOS developing and i'm looking for a solution to compare two String ignoring the spaces at the beginning or at the ending. For example, "Hello" == "Hello " should return true.
I've serached for a solution but i didn't find nothing in Swift. Thanks
I would recommend you start by trimming whitespace from the String with this Swift code:
stringToTrim.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
NSString *string1 = #" Hello";
//remove(trim) whitespaces
string1 = [string1 stringByReplacingOccurrencesOfString:#" " withString:#""];
NSString *string2 = #"Hello ";
//remove(trim) whitespaces
string2 = [string1 stringByReplacingOccurrencesOfString:#" " withString:#""]
// compare strings without whitespaces
if ([string1 isEuqalToString:string2]) {
}
So if you want to use it directly -
if ([[yourString1 stringByReplacingOccurrencesOfString:#" " withString:#""] isEuqalToString:[yourString2 stringByReplacingOccurrencesOfString:#" " withString:#""]]) {
// Strings are compared without whitespaces.
}
Above will remove all whitespaces of your string, if you want to remove only leading and trailing whitespaces then there are a couple of post already available, you can create a category of string as mentioned in following stack overflow post - How to remove whitespace from right end of NSString?
#implementation NSString (TrimmingAdditions)
- (NSString *)stringByTrimmingLeadingCharactersInSet:(NSCharacterSet *)characterSet {
NSUInteger location = 0;
NSUInteger length = [self length];
unichar charBuffer[length];
[self getCharacters:charBuffer];
for (location; location < length; location++) {
if (![characterSet characterIsMember:charBuffer[location]]) {
break;
}
}
return [self substringWithRange:NSMakeRange(location, length - location)];
}
- (NSString *)stringByTrimmingTrailingCharactersInSet:(NSCharacterSet *)characterSet {
NSUInteger location = 0;
NSUInteger length = [self length];
unichar charBuffer[length];
[self getCharacters:charBuffer];
for (length; length > 0; length--) {
if (![characterSet characterIsMember:charBuffer[length - 1]]) {
break;
}
}
return [self substringWithRange:NSMakeRange(location, length - location)];
}
#end
Now once you have the methods available, you can call these on your strings to trim leading and trailing spaces like -
// trim leading chars
yourString1 = [yourString1 stringByTrimmingLeadingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
// trim trainling chars
yourString1 = [yourString1 stringByTrimmingTrailingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
// trim leading chars
yourString2 = [yourString2 stringByTrimmingLeadingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
// trim trainling chars
yourString2 = [yourString2 stringByTrimmingTrailingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
// compare strings
if([yourString1 isEqualToString: yourString2]) {
}
For Swift 3.0+
Use .trimmingCharacters(in: .whitespaces) before comparison or .trimmingCharacters(in: .whitespacesAndNewlines)
In Swift 4
Use it on any String type variable.
extension String {
func trimWhiteSpaces() -> String {
let whiteSpaceSet = NSCharacterSet.whitespaces
return self.trimmingCharacters(in: whiteSpaceSet)
}
}
And Call it like this
yourString.trimWhiteSpaces()
I am writing code in objective-c. I would like to extract a url from a string.
Here is my code:
NSMutableString *oneContent = [[latestPosts objectAtIndex:i] objectForKey:#"content"];
NSLog(#"%#", oneContent);//no problem
NSString *string = #"http";
if ([oneContent rangeOfString:string].location == NSNotFound) {
NSLog(#"string does not contain substring");
} else {
NSLog(#"string contains substring!");
}
As you can see, I want to extract a url from the oneContent string, and I have checked that oneContent definitely contains "http", but why does the result show nothing?
Is there some better way to extract the url?
Check oneContent or the actual code you are running.
This works:
NSMutableString *oneContent = [#"asdhttpqwe" mutableCopy];
NSLog(#"%#", oneContent);//no problem
NSString *string = #"http";
if ([oneContent rangeOfString:string].location == NSNotFound) {
NSLog(#"string does not contain substring");
} else {
NSLog(#"string contains substring!");
}
NSLog output:
Untitled[5911:707] asdhttpqwe
Untitled[5911:707] string contains substring!
It is probably best not to use a Mutable string unless there is some substantial reason to do so.
I would suggest using NSScanner.
This simple validation method for NSString makes trouble.
I have an NSString value and I want to validate the string, i.e, if the string contains only 'a to z' (or) 'A to Z' (or) '1 to 9' (or) '#,!,&' then the string is valid. If the string contains any other values then this the NSString is invalid, how can i validate this..?
As example:
Valid:
NSString *str="aHrt#2"; // something like this
Invalid:
NSString *str="..gS$"; // Like this
Try using character sets:
NSMutableCharacterSet *set = [NSMutableCharacterSet characterSetWithCharactersInString:#"#!&"];
[set formUnionWithCharacterSet:[NSCharacterSet alphanumericCharacterSet]];
if ([string rangeOfCharacterFromSet:[set invertedSet]].location == NSNotFound) {
// contains a-z, A-Z, 0-9 and &#! only - valid
} else {
// invalid
}
I would do something using stringByTrimmingCharactersInSet
Create an NSCharacterSet containing all valid characters, then trim those characters from the test string, if the string is now empty it is valid, if there are any characters left over, it is invalid
NSCharacterSet *validCharacters = [NSCharacterSet characterSetWithCharactersInString:#"myvalidchars"];
NSString *trimmedString = [testString stringByTrimmingCharactersInSet:validCharachters];
BOOL valid = [trimmedString length] == 0;
Edit:
If you want to control the characters that can be entered into a text field, use textField:shouldChangeCharactersInRange:replacementString: in UITextFieldDelegate
here the testString variable becomes the proposed string and you return YES if there are no invalid characters
The NSPredicate class is what you want
More info about predicate programming. Basically you want "self matches" (your regular expression). After that you can use the evaluateWithObject: method.
EDIT Easier way: (nevermind, as I am editing it wattson posted what I was going to)
You can use the class NSRegularExpression to do this.
https://developer.apple.com/library/mac/documentation/Foundation/Reference/NSRegularExpression_Class/Reference/Reference.html
You can also use NSRegularExpression to search your NSString, if it contains only the valid characters (or vice versa).
More info:
Search through NSString using Regular Expression
Use regular expression to find/replace substring in NSString
- (BOOL)validation:(NSString *)string
{
NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:#"1234567890abcdefghik"] invertedSet];
NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:#""];
return ([string isEqualToString:filtered]);
}
In your button action:
-(IBAction)ButtonPress{
if ([self validation:activity.text]) {
NSLog(#"Macth here");
}
else {
NSLog(#"Not Match here");
}
}
Replace this "1234567890abcdefghik" with your letters with which you want to match
+(BOOL) validateString: (NSString *) string
{
NSString *regex = #"[A-Z0-9a-z#!&]";
NSPredicate *test = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", emailRegex];
BOOL isValid = [test evaluateWithObject:string];
return isValid;
}
You can simply do it using NSMutableCharacterSet
NSMutableCharacterSet *charactersToKeep = [NSMutableCharacterSet alphanumericCharacterSet];
[charactersToKeep addCharactersInString:#"#?!"];
NSCharacterSet *charactersToRemove = [charactersToKeep invertedSet]
NSString *trimmed = [ str componentsSeparatedByCharactersInSet:charactersToRemove];
if([trimmed length] != 0)
{
//invalid string
}
Reference NSCharacterSet
You can use regex. If every thing fails use brute force like
unichar c[yourString.length];
NSRange raneg={0,2};
[yourString getCharacters:c range:raneg];
// now in for loop
for(int i=0;i<yourString.length;i++)
{
if((c[i]>='A'&&c[i]<='Z')&&(c[i]=='#'||c[i]=='!'||c[i]=='&'))
{
//not the best or most efficient way but will work till you write your regex:P
}
}
How can I uppercase the fisrt letter of a NSString, and removing any accents ?
For instance, Àlter, Alter, alter should become Alter.
But, /lter, )lter, :lter should remains the same, as the first character is not a letter.
Please Do NOT use this method. Because one letter may have different count in different language. You can check dreamlax answer for that. But I'm sure that You would learn something from my answer.
NSString *capitalisedSentence = nil;
//Does the string live in memory and does it have at least one letter?
if (yourString && yourString.length > 0) {
// Yes, it does.
capitalisedSentence = [yourString stringByReplacingCharactersInRange:NSMakeRange(0,1)
withString:[[yourString substringToIndex:1] capitalizedString]];
} else {
// No, it doesn't.
}
Why should I care about the number of letters?
If you try to access (e.g NSMakeRange, substringToIndex etc)
the first character in an empty string like #"", then your app will crash. To avoid this you must verify that it exists before processing on it.
What if my string was nil?
Mr.Nil: I'm 'nil'. I can digest anything that you send to me. I won't allow your app to crash all by itself. ;)
nil will observe any method call you send to it.
So it will digest anything you try on it, nil is your friend.
You can use NSString's:
- (NSString *)capitalizedString
or (iOS 6.0 and above):
- (NSString *)capitalizedStringWithLocale:(NSLocale *)locale
Since you want to remove diacritic marks, you could use this method in combination with the common string manipulating methods, like this:
/* create a locale where diacritic marks are not considered important, e.g. US English */
NSLocale *locale = [[[NSLocale alloc] initWithLocaleIdentifier:#"en-US"] autorelease];
NSString *input = #"Àlter";
/* get first char */
NSString *firstChar = [input substringToIndex:1];
/* remove any diacritic mark */
NSString *folded = [firstChar stringByFoldingWithOptions:NSDiacriticInsensitiveSearch locale:locale];
/* create the new string */
NSString *result = [[folded uppercaseString] stringByAppendingString:[input substringFromIndex:1]];
Gonna drop a list of steps which I think you can use to get this done. Hope you can follow through without a prob! :)
Use decomposedStringWithCanonicalMappingto decompose any accents (Important to make sure accented characters aren't just removed unnecessarily)
Use characterAtIndex: to extract the first letter (index 0), use upperCaseString to turn it into capitol lettering and use stringByReplacingCharactersInRange to replace the first letter back into the original string.
In this step, BEFORE turning it into uppercase, you can check whether the first letter is one of the characters you do not want to replace, e.g. ":" or ";", and if it is, do not follow through with the rest of the procedure.
Do a [theString stringByReplacingOccurrencesOfString:#"" withString:#""]` sort of call to remove any accents left over.
This all should both capitalize your first letter AND remove any accents :)
Since iOS 9.0 there is a method to capitalize string using current locale:
#property(readonly, copy) NSString *localizedCapitalizedString;
I'm using this method for similar situations but I'm not sure if question asked to make other letters lowercase.
- (NSString *)capitalizedOnlyFirstLetter {
if (self.length < 1) {
return #"";
}
else if (self.length == 1) {
return [self capitalizedString];
}
else {
NSString *firstChar = [self substringToIndex:1];
NSString *otherChars = [self substringWithRange:NSMakeRange(1, self.length - 1)];
return [NSString stringWithFormat:#"%#%#", [firstChar uppercaseString], [otherChars lowercaseString]];
}
}
Just for adding some options, I use this category to capitalize the first letter of a NSString.
#interface NSString (CapitalizeFirst)
- (NSString *)capitalizeFirst;
- (NSString *)removeDiacritic;
#end
#implementation NSString (CapitalizeFirst)
- (NSString *)capitalizeFirst {
if ( self.length <= 1 ) {
return [self uppercaseString];
}
else {
return [[[[self substringToIndex:1] removeDiacritic] uppercaseString] stringByAppendingString:[[self substringFromIndex:1] removeDiacritic]];
// Or: return [NSString stringWithFormat:#"%#%#", [[[self substringToIndex:1] removeDiacritic] uppercaseString], [[self substringFromIndex:1] removeDiacritic]];
}
}
- (NSString *)removeDiacritic { // Taken from: http://stackoverflow.com/a/10932536/1986221
NSData *data = [NSData dataUsingEncoding:NSASCIIStringEncoding
allowsLossyConversion:YES];
return [[NSString alloc] initWithData:data
encoding:NSASCIIStringEncoding];
}
#end
And then you can simply call:
NSString *helloWorld = #"hello world";
NSString *capitalized = [helloWorld capitalizeFirst];
NSLog(#"%# - %#", helloWorld, capitalized);
Iam developing one applciation.In that i want to comapare the every character of string with other character.So please tell me how to do that one.
Use characterAtIndex: function of NSString to extract the character by index.
- (unichar)characterAtIndex:(NSUInteger)index
for (int i=0; i<[string length]; i++) {
char = [string characterAtIndex:i];
NSString *charString = [NSString stringWithFormat:#"%c", char];
if ([charString isEqualToString:comparisonString]) {
//match
}
else {
//no match
}
}
if you want to compare a string. Using isEqualToString method.
NSMutableString *str = [[NSMutableString alloc] initWithString:#"a"];
if([str isEqualToString:#"a"]){
// match
}
else{
// not match
}