In my app I read contacts from address book, but for some of them, the name fields is empty. I want to put them at the end of my list by using a special string. What sort of special string should I use to make sure when the array is getting sorted ascending, person with missing name is placed at the end of the array?
for example my name array is
array = #[#"Andy", #"Brad", #"Zoro", #"[missing name]"];
[array sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
I have tried using <UNKNOWN NAME> or [UNKNOWN NAME] or <UNKONWN NAME> but they all turned out to be in earlier position than Andy
Thank you in advance.
Conventional
Don't use a special string for missing names; don't do unnatural things just because you are missing data. Write your own message that uses localizedCaseInsensitiveCompare:, and put it in your own category on NSString.
// NSStringEmptyLast.h
#interface NSString (EmptyLast)
- (NSComparisonResult)localizedCaseInsensitiveCompareEmptyLast:(NSString *)aString
#end
// NSStringEmptyLast.m
#import NSStringEmptyLast.h
#implementation NSString (EmptyLast)
- (NSComparisonResult)localizedCaseInsensitiveCompareEmptyLast:(NSString *)aString {
if ([self length] == 0 && [aString length] == 0) {
return NSOrderedSame;
} else if ([self length] == 0 && [aString length] != 0) {
return NSOrderedDescending;
} else if ([self length] != 0 && [aString length] == 0) {
return NSOrderedAscending;
} else {
return [self localizedCaseInsensitiveCompare:aString];
}
}
#end
Then, use:
[array sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompareEmptyLast:)];
Don't be afraid to add messages for existing classes.
Blocks
Or, if you don't want to write a category, use
- (NSArray *)sortedArrayUsingComparator:(NSComparator)cmptr
where cmptr is a NSComparator block, which should have the equivalent of the message given above.
Try using curly brackets: {…}, pipe: |, or tilde: ~.
Here is what I ended up with. Since I want to avoid array sorting after query from the database. I setup a fake string to people that doesn't have name. This might not be the most elegant answer but it will make people with this name appear last if I query from core data using name in ascending order.
// Person+UnknownName.h
#interface Person (UnknownName)
+ (NSString)unknownName
#end
// Person+UnknownName.m
#import "Person+UnknownName.h"
#implementation Person (UnknownName)
+ (NSString)unknownName {
unichar lastcharacter = 0xffffffff;
NSString * UNKNOWN_NAME = [NSString stringWithCharacters:&lastcharacter length:1];
}
#end
Related
I'm having trouble with a school problem in Objective C. I need to build 3 methods. The first method tells you if someone is in a line. If nobody is in the line it tells you nobody is in the line otherwise it tells you who is in the line and it lists the names on a new line.
The second method adds names to the line.
The third method removes a name from the line and tells you who was removed.
First method:
-(NSString*)stringWithDeliLine:(NSArray*) deliLine{
NSString *empty = #"The line is currently empty.";
//Some kind of formatted string
if(deliLine == nil || [deliLine count] == 0)
{
empty;
}
else
{
//formatted string
}
//not sure how to return either empty or formatted string
}
Second Method:
-(void)addName:toDeliLine:(NSString*)name:(NSMutableArray*)deliLine{
[deliLine addObject:name];
}
The third method I was going to use removeObject but the instructions said not to use it so I have no idea where to start.I have the signature I think.
-(NSString*)serveNextCustomerInDeliLine:(NSMutableArray*)deliLine{
return nil;
}
For the first method I'm not sure why my literal string won't work in the if statement. I thought I was saying look at the array if nothing is in the array then it's the first object and show the string literal. else show some kinda of formatted string. I've tried all kinds of strings but none seem to be working so that's why I have the comment formatted string. If someone could give me a hint that would be great. I don't need the answer just a clue on what to think about. This is long post sorry.
A possible implementation can be the following. Please note that I have not testes edge cases and I wrote the code without Xcode support
#import <Foundation/Foundation.h>
#interface Line : NSObject
- (NSString*)printLine;
- (void)addCustomer:(NSString*)customer;
- (NSString*)removeCustomer:(NSString*)customer;
#end
#import "Line.h"
#interface Line ()
#property (nonatomic, strong, readwrite) NSMutableArray<NSString*> *customers;
#end
#implementation Line
- (instancetype)init {
self = [super init];
if (self) {
_customers = [NSMutableArray array];
}
return self;
}
- (NSString*)printLine {
NSUInteger count = self.customers.count;
if(count == 0) {
return #"Empty";
}
NSMutableString *descr = [NSMutableString string];
for (NSString *customer in self.customers) {
[descr appendString:[NSString stringWithFormat:#"%# ", customer]];
}
return [descr copy];
}
- (void)addCustomer:(NSString*)customer {
[self.customers addObject:customer];
}
- (NSString*)removeCustomer:(NSString*)customer {
NSUInteger index = [self.customers indexOfObject:customer];
if(index == NSNotFound) {
return [NSString stringWithFormat:#"%# not removed", customer];
}
NSString *removedCustomer = [self.customers objectAtIndex:index];
[self.customers removeObjectAtIndex:index];
return removedCustomer;
}
#end
Usage:
Line *line = [[Line alloc] init];
[line addCustomer:#"customer"];
NSLog(#"%#", [line printLine]);
NSLog(#"%#", [line removeCustomer:#"customer"]);
NSLog(#"%#", [line printLine]);
Edit:
I've updated my answer, passing the array as a parameter is not necessary, just initialize deliLine as a mutable array property.
For you first method, you could do the following,
- (NSString *)deliLineContents {
NSString *empty = #"The line is currently empty.";
NSMutableString *namesInQueue = [[NSMutableString alloc] init];
if(self.deliLine == nil || [self.deliLine count] == 0) {
return empty;
} else {
// Loop through your array and return a string of all the names
for (NSString *string in self.deliLine ) {
[namesInQueue appendString:string];
}
}
return [NSString stringWithString:namesInQueue];
For your second method, you're already pretty much there, maybe look up how to construct method signatures.
- (void)addNameToDeliLine:(NSString*)name {
[self.deliLine addObject:name];
}
For your third method, not sure if this meets your requirement, if not let me know.
- (NSString *)customerRemovedFromLine {
// I've making an assumption that you want to remove the first customer
NSString *servedCustomer = [self.deliLine objectAtIndex:0];
[self.deliLine removeObjectAtIndex:0];
return servedCustomer;
}
You probably don't need to pass deliLine around, just create it as a property and access it with self.deliLine. Anyway hope this helps, good luck.
please help me with this problem.
I want to check if the targetString match the keyword or not. Consider some character may different, but should still return true.
Example:
targetString = #"#ß<"
keyword = #"abc", #"∂B(", #"#Aß<"
result: all must return true.
(Matched.targetString and all keyword are the same.)
Consider me have an array, contains list of character set that can be the same:
NSArray *variants = [NSArray arrayWithObjects:#"aA#∂", #"bBß", #"c©C<(", nil]
So that when matching, with this rule, it can match as the example above.
Here is what i've done so far (using recursion):
- (BOOL) test:(NSString*)aString include:(NSString*) keyWord doTrim:(BOOL)doTrim {
// break recursion.
if([aString length] < [keyWord length]) return false;
// First, loop through each keyword's character
for (NSUInteger i = 0; i < [keyWord length]; i++) {
// Get #"aA#∂", #"bBß", #"c©C<(" or only the character itself.
// like, if the keyword's character is A, return the string #"aA#∂".
// If the character is not in the variants set, eg. P, return #"P"
char c = [keyWord characterAtIndex:i];
NSString *rs = [self variantsWithChar:c];
// Check if rs (#"aA#∂" or #"P") contains aString[i] character
if([rs rangeOfString:[NSString stringWithCharacters:[aString characterAtIndex:i] length:1]].location == NSNotFound) {
// If not the same char, remove first char in targetString (aString), recursion to match again.
return [self test:[aString substringFromIndex:1] include:keyWord doTrim:NO];
}
}
// If all match with keyword, return true.
return true;
}
- (NSString *) variantsWithChar:(char) c {
for (NSString *s in self.variants) {
if ([s rangeOfString:[NSString stringWithFormat:#"%c",c]].location != NSNotFound) {
return s;
}
}
return [NSString stringWithFormat:#"%c", c];
}
The main problem is, variantsWithChar: doesn't return the correct string. I don't know which datatype and which function should I use here. Please help.
For thou who know ruby, here's the example in ruby. It work super fine!
require 'test/unit/assertions'
include Test::Unit::Assertions
class String
def matching?(keyword)
length >= keyword.length && (keyword.chars.zip(chars).all? { |cs| variants(cs[0]).include?(cs[1]) } || slice(1, length - 1).matching?(keyword))
end
private
VARIANTS = ["aA#∂", "bBß", "c©C<("]
def variants(c)
VARIANTS.find { |cs| cs.include?(c) } || c
end
end
assert "abc".matching?("#ß<")
PS: The fact is, it's containt a japanese character set that sounds the same (like あア, いイ... for thou who know japanese)
PS 2: Please feel free to edit this Question, since my engrish is sooo bad. I may not tell all my thought.
PS 3: And, maybe some may comment about the performance. Like, search about 10,000 target words, with nearly 100 variants, each variant have at most 4 more same characters.
So first off, ignore comments about ASCII and stop using char. NSString and CFString use unichar
If what you really want to do is transpose hiragana and katakana you can do that with CFStringTransform()
It wraps the ICU libraries included in OS X and iOS.
It makes it very simple.
Search for that function and you will find examples of how to use it.
After a while (a day) working on the code above, I finally get it through. But don't know about the performance. Someone comment and help me improve about performance, please. Thanks.
- (BOOL) test:(NSString*)aString include:(NSString*) keyWord doTrim:(BOOL)doTrim {
// break recursion.
if([aString length] < [keyWord length]) return false;
// First, loop through each keyword's character
for (NSUInteger i = 0; i < [keyWord length]; i++) {
// Get #"aA#∂", #"bBß", #"c©C<(" or only the character itself.
// like, if the keyword's character is A, return the string #"aA#∂".
// If the character is not in the variants set, eg. P, return #"P"
NSString* c = [NSString stringWithFormat:#"%C", [keyWord characterAtIndex:i]];
NSString *rs = [self variantsWithChar:c];
NSString *theTargetChar = [NSString stringWithFormat:#"%C", [aString characterAtIndex:i]];
// Check if rs (#"aA#∂" or #"P") contains aString[i] character
if([rs rangeOfString:theTargetChar].location == NSNotFound) {
// If not the same char, remove first char in targetString (aString), recursion to match again.
return [self test:[aString substringFromIndex:1] include:keyWord doTrim:NO];
}
}
// If all match with keyword, return true.
return true;
}
If you remove all comment, it'll be pretty short...
////////////////////////////////////////
- (NSString *) variantsWithChar:(NSString *) c{
for (NSString *s in self.variants) {
if ([s rangeOfString:c].location != NSNotFound) {
return s;
}
}
return c;
}
You could try comparing ascii values of the japanese characters in the variants's each character's ascii value. These japanese characters aren't treated like usual characters or string. Hence, string functions like rangeOfString won't work on them.
to be more precise: have a look at the following code.
it will search for "∂" in the string "aA#∂"
NSString *string = #"aA#∂";
NSMutableSet *listOfAsciiValuesOfString = [self getListOfAsciiValuesForString:string]; //method definition given below
NSString *charToSearch = #"∂";
NSNumber *ascii = [NSNumber numberWithInt:[charToSearch characterAtIndex:0]];
int countBeforeAdding = [listOfAsciiValuesOfString count],countAfterAdding = 0;
[listOfAsciiValuesOfString addObject:ascii];
countAfterAdding = [listOfAsciiValuesOfString count];
if(countAfterAdding == countBeforeAdding){ //element found
NSLog(#"element exists"); //return string
}else{
NSLog(#"Doesnt exists"); //return char
}
===================================
-(NSMutableSet*)getListOfAsciiValuesForString:(NSString*)string{
NSMutableSet *set = [[NSMutableSet alloc] init];
for(int i=0;i<[string length];i++){
NSNumber *ascii = [NSNumber numberWithInt:[string characterAtIndex:i]];
[set addObject:ascii];
}
return set;
}
I was writing a small Category on NSString, and I wanted to know if this method is accurately handles all potential use cases:
Update: to clarify -- I wanted to make sure I'm not missing some oddball case involving character encodings, etc..
#implementation NSString (Helpers)
+(BOOL)stringIsNilOrEmpty:(NSString*)aString {
if (!aString)
return YES;
return [aString isEqualToString:#""];
}
#end
Sample usage:
-(void) sampleUsage {
NSString *emptyString = #"";
NSString *nilString = nil;
NSAssert([NSString stringIsNilOrEmpty:nilString] == YES, #"String is nil/empty");
NSAssert([NSString stringIsNilOrEmpty:emptyString] == YES, #"String is nil/empty");
}
#end
I only use the next conditional and do not even need a category:
if (!aString.length)
{
...
}
Using Objective-C theory, a message to NIL will return nil or zero, so basically you do not have to test for nil.
You can simplify the code by removing conditional:
+(BOOL)stringIsNilOrEmpty:(NSString*)aString {
return !(aString && aString.length);
}
#dasblinkenlight's answer is fine, but a much more readable conditional check I would use is:
NSString *string = ...; // define the string
if ([string length] == 0) {
// Do stuff with the string
} else {
// The string is empty or nil here
}
Very concise and does not require a separate convenience function definition. It's easy enough to remember.
EDIT: #Michael G. Emmons posted this as the last comment to that answer... credit to him but I'm listing this as an answer in its own right.
Some examples of this sort of "is not empty or blank" tests as a category on NSString.
// Please note that in general I advocate using a prefix on category methods
// to avoid category collisions. I've not done this here for clarity.
// The #interface is also excluded from this example for brevity.
#implementation NSString (MyAdditions)
- (BOOL)isNotEmpty
{
return [self length] != 0;
}
- (BOOL)isNotBlank
{
if ([self isNotEmpty])
{
NSCharacterSet *nonWhitespaceSet = [[NSCharacterSet whitespaceAndNewlineCharacterSet] invertedSet];
NSRange range = [self rangeOfCharactersFromSet:nonWhitespaceSet];
return range.location != NSNotFound;
}
return NO;
}
#end
Simply Check your string length
> if (!yourString.length){
> //your code } a
message to NIL will return nil or 0, so no need to test for nil :).
Happy coding ...
Make sure to check for spaces, trim white spaces before calculating length.
+(BOOL)stringIsNilOrEmpty:(NSString*)aString {
return !aString || [[aString stringByTrimmingCharactersInSet:
[NSCharacterSet whitespaceCharacterSet]] length] == 0;
}
I'm making little utility to help me generate code for an app I'm making. I like to have constants for my NSUserDefaults settings, so that my code is more readable and easier to maintain. The problem is, that making constants for everything takes some time, so I'm trying to write a utility to generate code for me. I'd like to be able to enter a string and have it converted to camel case, like so:
- (NSString *)camelCaseFromString:(NSString *)input{
return inputAsCamelCase;
}
Now, the input string might be composed of multiple words. I'm assuming that I need some sort of regular expression here, or perhaps there is another way to do it. I'd like to input something like this:
#"scrolling direction"
or this:
#"speed of scrolling"
and get back something like this:
kScrollingDirection
or this:
kSpeedOfScrolling
How would you go about removing spaces and replacing the character following the space with the uppercase version?
- (NSString *)camelCaseFromString:(NSString *)input {
return [#"k" stringByAppendingString:[[input capitalizedString] stringByReplacingOccurrencesOfString:#" " withString:#""]];
}
Capitalize each word.
Remove whitespace.
Insert "k" at the beginning. (Not literally, but a simplification using stringByAppendingString.)
The currently accepted answer has a bug. (also pointed out by #jaydee3)
Words already having proper camelCasing, PascalCasing, or capitalized TLA acronyms will have their correct casing "destroyed" by having non-first characters lowercased via the call to capitalizedString.
So "I prefer camelCasing to PascalCasing for variables" would look like "iPreferCamelcasingToPascalcasingForVariables" but according to the question, should be "iPreferCamelCasingToPascalCasingForVariables"
Use the below category on NSString to create non-destructive camel and pascal casing. It also properly leaves ALL_CAPS words/acronyms in place, although that wasn't really part of the orig question.
An acronym as a first word for a camelCased string would be weird. "WTH" becomes "wTH" which looks weird. Anyway, that's an edge case, and not addressed. However, since question asker is prefixing with "k" then it "k IBM" becomes "kIBM" which looks ok to me, but would look be "kIbm" with currently accepted answer.
Use:
NSString *str = #"K computer manufacturer IBM";
NSLog(#"constant: %#", str.pascalCased);
// "constant: kComputerManufacturerIBM"
Category (class extension) code.
#implementation NSString (MixedCasing)
- (NSString *)camelCased {
NSMutableString *result = [NSMutableString new];
NSArray *words = [self componentsSeparatedByString: #" "];
for (uint i = 0; i < words.count; i++) {
if (i==0) {
[result appendString:((NSString *) words[i]).withLowercasedFirstChar];
}
else {
[result appendString:((NSString *)words[i]).withUppercasedFirstChar];
}
}
return result;
}
- (NSString *)pascalCased {
NSMutableString *result = [NSMutableString new];
NSArray *words = [self componentsSeparatedByString: #" "];
for (NSString *word in words) {
[result appendString:word.withUppercasedFirstChar];
}
return result;
}
- (NSString *)withUppercasedFirstChar {
if (self.length <= 1) {
return self.uppercaseString;
} else {
return [NSString stringWithFormat:#"%#%#",[[self substringToIndex:1] uppercaseString],[self substringFromIndex:1]];
}
}
- (NSString *)withLowercasedFirstChar {
if (self.length <= 1) {
return self.lowercaseString;
} else {
return [NSString stringWithFormat:#"%#%#",[[self substringToIndex:1] lowercaseString],[self substringFromIndex:1]];
}
}
#end
Just use: #"This is a sentence".capitalizedString;
Becomes: >> "This Is A Sentence"
Replace spaces and manipulate...
Uppercases first char of word, and lowers the other letters for each word.
Hey folks, beneath is a piece of code i used for a school assignment.
Whenever I enter a word, with an O in it (which is a capital o), it fails!
Whenever there is one or more capital O's in this program, it returns false and logs : sentence not a palindrome.
A palindrome, for the people that dont know what a palindrome is, is a word that is the same read left from right, and backwards. (e.g. lol, kayak, reviver etc)
I found this bug when trying to check the 'oldest' palindrome ever found: SATOR AREPO TENET OPERA ROTAS.
When I change all the capital o's to lowercase o's, it works, and returns true.
Let me state clearly, with this piece of code ALL sentences/words with capital O's return false. A single capital o is enough to fail this program.
-(BOOL)testForPalindrome:(NSString *)s position:(NSInteger)pos {
NSString *string = s;
NSInteger position = pos;
NSInteger stringLength = [string length];
NSString *charOne = [string substringFromIndex:position];
charOne = [charOne substringToIndex:1];
NSString *charTwo = [string substringFromIndex:(stringLength - 1 - position)];
charTwo = [charTwo substringToIndex:1];
if(position > (stringLength / 2)) {
NSString *printableString = [NSString stringWithFormat:#"De following word or sentence is a palindrome: \n\n%#", string];
NSLog(#"%# is a palindrome.", string);
[textField setStringValue:printableString];
return YES;
}
if(charOne != charTwo) {
NSLog(#"%#, %#", charOne, charTwo);
NSLog(#"%i", position);
NSLog(#"%# is not a palindrome.", string);
return NO;
}
return [self testForPalindrome:string position:position+1];
}
So, is this some weird bug in Cocoa?
Or am I missing something?
B
This of course is not a bug in Cocoa, as you probably knew deep down inside.
Your compare method is causing this 'bug in Cocoa', you're comparing the addresses of charOne and charTwo. Instead you should compare the contents of the string with the isEqualToString message.
Use:
if(![charOne isEqualToString:charTwo]) {
Instead of:
if(charOne != charTwo) {
Edit: tested it in a test project and can confirm this is the problem.
Don't use charOne != charTwo
Instead use one of the NSString Compare Methods.
if ([charOne caseInsensitiveCompare:charTwo] != NSOrderedSame)
It may also have to do with localization (but I doubt it).