I'm trying to create a string containing (unicode) 'stars' based on an integer rating. I currently have:
NSMutableString *stars = [NSMutabelString stars];
for (int i = 0; i < rating; i++)
{
[stars appendString:#"\u2605"];
}
However, I find this a bit ugly. Does a way exist to construct such a string without using this looping method? Something using the string formats?
Sure - to do this on a single line you can use the stringByPaddingToLength method:
[#"" stringByPaddingToLength: rating withString: #"\u2605" startingAtIndex:0];
...should hopefully do the trick for you - and no need to create any subclasses or categories, etc!
You can make a category for NSString with an extra method - say, +(NSString)stringForRating:(NSInteger)rating, and move the loop in there. Then whenever you need a star string, just call that.
Related
It may be a simple question, but i could't get the answer and needing your help!
I have a string like,
NSString *temp = #"Hello How are you?";
I have to provide spaces dynamically starting in this string by code. For ex: I need to dynamically add 5 spaces in this string in starting point. So, the output string will be like,
#" Hello how are you?"
My doubt is, how can i add spaces dynamically to a existing string? I need it to do this way only, not via any other way like string concatenation etc. due to my requirement.
So, please advise me how can i add spaces dynamically in starting point of the existing string.
Note: The spaces will vary every time, its not constant that i can provide 5 spaces only, it will vary.
Thank you!
An NSString is immutable, so you have to create a new string in any case.
The following code will create a front-padded string with padLength spaces:
int padLength = 10;
NSString* originalString = #"original";
NSString* leadingSpaces = [#"" stringByPaddingToLength:padLength];
NSString* resultString = [NSString stringWithFormat:#"%#%#", leadingSpaces, originalString];
this is hard to describe but I am currently catching a string from a database, this string can be 1-4 characters long, however I am wanting to always display 4 characters, so if i get say a string back that is 34, i want it to be 0034.
I have set up a method to catch the string so now I just need to figure out how to do this. what I then plan to do is feed that string into a NSArray so I can send each [i'th] of the array off to 4 differetn methods that control animations in my app.
The reason its in string format is because I have had to bounce it round from hex, to int to string for various formatting reasons within the application.
this is my code i have so far. Suggestions/solutions would be great thankyou, I am so new its hard to find solutions for stuff like string manipulation etc..
//... other method I am getting the string from/.
[self formatMyNumber:dataString];
///..
-(void)formatMyNumber:(NSString *)numberString{
//resultLabel.text = numberString; //check to make sure string makes it to here.
//NSLog(#"hello From formatMyNumber method"); //check
}
//..
//the with send off each character to 4 animation methods that accept integers.
- (void)playAnimationToNumber:(int)number{
//...
//UpDated... weird stuff happening.
here is my method so far.
//Number Formatter
-(void)formatMyNumber:(NSString *)numberString{
NSLog(#"This is what is passed into the method%#",numberString);
int tempInt = (int)numberString;
NSLog(#"This is after I cast the string to an int %i",tempInt);
//[NSString alloc] stringWithFormat:#"%04d", numberString];
NSString *tempString = [[NSString alloc] initWithFormat:#"%04d", tempInt];
NSLog(#"This is after I try to put zeros infront %#",tempString);
//resultLabel.text = tempString;
//NSLog(#"hello From formatMyNumber method");
}
this is the output.
[Session started at 2011-06-19
16:18:45 +1200.] 2011-06-19
16:18:54.615 nissanCode0.1[4298:207]
731 2011-06-19 16:18:54.616
nissanCode0.1[4298:207] 79043536
2011-06-19 16:18:54.617
nissanCode0.1[4298:207] 79043536
2011-06-19 16:18:54.617
nissanCode0.1[4298:207] hello From
formatMyNumber method
As far as the number of zeros preceding your string goes there are a couple of ways to do this. I'd suggest:
NSString *myString = [NSString stringWithFormat:#"%04d",[dataString intValue]];
Is it possible you could have the number in integer form instead of string form? If so, it's pretty easy to use [NSString stringWithFormat:#"%04d", number]. See here for a list of the possible format specifiers.
See what stringWithFormat: can do. I realize you mentioned your numbers are NSStrings, but if they were ints, or you convert them back to ints, the following may do the trick. Modify the following to best suit your need:
return [NSString stringWithFormat:#"%04d", number];
I am confused about strings (a beginner's problem, I'm afraid):
I have one NSMutableArray called Notebook. At index position 1, I have an object, which I think is a string. At least I put it into the array like this:
[NoteBook replaceObjectAtIndex:1 withObject:#"x-x-x-x"];
So far so good. If I put this into an UILabel, it will show x-x-x-x on my screen. The nightmare starts when I try to compare this string with other strings. Let's consider that I do not want to display the string x-x-x-x on my screen, but just to have a blank instead. So I thought I could achieve this by coding this:
NSString *tempDateString;
tempDateString = [NSString stringWithFormat:#"%#",[NoteBook objectAtIndex:1]];
if (tempDateString == #"x-x-x-x") {
UISampleLabel.text = #"";
}
For some reason, this does not work, i.e. even if the string at position 1 of my array is 'x-x-x-x', it will still not set my UISampleLabel to nothing.
I suppose that I am getting confused with the #"" markers. When do I really need them? Why can't I simply code tempDateString = [NoteBook objectAtIndex:1]; without the formatting thing?
Any help and suggestions would be very much appreciated!
You need to compare string with isEqualToString:
if ([tempDateString isEqualToString:#"x-x-x-x"]) {
UISampleLabel.text = #"";
}
In addition to the question that's been answered:
Why can't I simply code tempDateString = [NoteBook objectAtIndex:1]; without the formatting thing?
You can. Why do you think you can't?
m anew comer to iPhone...before i have developed for Android..Could any one tell me what is the alternate code in objective C..Thanx in advance
Int projectNumber = Integer.parseInt(projectNumber.trim());
int intProjectNumber = [[projectNumber stringByTrimmingCharactersInSet:whitespaceCharacterSet] integerValue];
edit:
Just to explain a bit more..
If you have a NSString named projectNumber (ie. #" 4 "). You can make a new string with trimed whitespace infront of the string and after the string with
NSString *trimedProjectNumber = [projectNumber stringByTrimmingCharactersInSet:whitespaceCharacterSet];
as you can see this replaces the trim() function
trimedProjectNumber would now be #"4". If you want an integer representation of this string you do:
int intProjectNumber = [trimedProjectNumber integerValue];
this replaces the parseInt..
I dont know java but i think this is what youre code does? If not explain what the java code does..
Based on this SO question asked a few hours ago, I have decided to implement a swizzled method that will allow me to take a formatted NSString as the format arg into stringWithFormat, and have it not break when omitting one of the numbered arg references (%1$#, %2$#)
I have it working, but this is the first copy, and seeing as this method is going to be potentially called hundreds of thousands of times per app run, I need to bounce this off of some experts to see if this method has any red flags, major performance hits, or optimizations
#define NUMARGS(...) (sizeof((int[]){__VA_ARGS__})/sizeof(int))
#implementation NSString (UAFormatOmissions)
+ (id)uaStringWithFormat:(NSString *)format, ... {
if (format != nil) {
va_list args;
va_start(args, format);
// $# is an ordered variable (%1$#, %2$#...)
if ([format rangeOfString:#"$#"].location == NSNotFound) {
//call apples method
NSString *s = [[[NSString alloc] initWithFormat:format arguments:args] autorelease];
va_end(args);
return s;
}
NSMutableArray *newArgs = [NSMutableArray arrayWithCapacity:NUMARGS(args)];
id arg = nil;
int i = 1;
while (arg = va_arg(args, id)) {
NSString *f = [NSString stringWithFormat:#"%%%d\$\#", i];
i++;
if ([format rangeOfString:f].location == NSNotFound) continue;
else [newArgs addObject:arg];
}
va_end(args);
char *newArgList = (char *)malloc(sizeof(id) * [newArgs count]);
[newArgs getObjects:(id *)newArgList];
NSString* result = [[[NSString alloc] initWithFormat:format arguments:newArgList] autorelease];
free(newArgList);
return result;
}
return nil;
}
The basic algorithm is:
search the format string for the %1$#, %2$# variables by searching for %#
if not found, call the normal stringWithFormat and return
else, loop over the args
if the format has a position variable (%i$#) for position i, add the arg to the new arg array
else, don't add the arg
take the new arg array, convert it back into a va_list, and call initWithFormat:arguments: to get the correct string.
The idea is that I would run all [NSString stringWithFormat:] calls through this method instead.
This might seem unnecessary to many, but click on to the referenced SO question (first line) to see examples of why I need to do this.
Ideas? Thoughts? Better implementations? Better Solutions?
Whoa there!
Instead of screwing with a core method that you very probably will introduce subtle bugs into, instead just turn on "Static Analyzer" in your project options, and it will run every build - if you get the arguments wrong it will issue a compiler warning for you.
I appreciate your desire to make the application more robust but I think it very likely that re-writing this method will more likely break your application than save it.
How about defining your own interim method instead of using format specifiers and stringWithFormat:? For example, you could define your own method replaceIndexPoints: to look for ($1) instead of %1$#. You would then format your string and insert translated replacements independently. This method could also take an array of strings, with NSNull or empty strings at the indexes that don't exist in the “untranslated” string.
Your method could look like this (if it were a category method for NSMutableString):
- (void) replaceIndexPointsWithStrings:(NSArray *) replacements
{
// 1. look for largest index in "self".
// 2. loop from the beginning to the largest index, replacing each
// index with corresponding string from replacements array.
}
Here's a few issues that I see with your current implementation (at a glance):
The __VA_ARGS__ thingy explained in the comments.
When you use while (arg = va_arg(args, id)), you are assuming that the arguments are nil terminated (such as for arrayWithObjects:), but with stringWithFormat: this is not a requirement.
I don't think you're required to escape the $ and # in your string format in your arg-loop.
I'm not sure this would work well if uaStringWithFormat: was passed something larger than a pointer (i.e. long long if pointers are 32-bit). This may only be an issue if your translations also require inserting unlocalised numbers of long long magnitude.