How to print a array element at particular index in Objective-C? My code looks like this:
NSString *String=[NSString StringWithContentsOFFile:#"/User/Home/myFile.doc"];
NSString *separator = #"\n";
NSArray *array = [String componetntsSeparatedByString:separator];
NSLog(#"%#",array);
I'm able to print the full contents of an array at once, but I want to assign the element at each index into a string, like...
str1=array[0];
str2=array[1];
str3=array[0];...this continues
How do I do this?
You want the objectAtIndex: method. Example:
NSString *str1 = [array objectAtIndex:0];
NSString *str2 = [array objectAtIndex:1];
NSString *str3 = [array objectAtIndex:2];
From the documentation:
objectAtIndex:
Returns the object located at index.
- (id)objectAtIndex:(NSUInteger)index
Parameters
index
An index within the bounds of the receiver.
Return Value
The object located at index.
Discussion
If index is beyond the end of the array (that is, if index is greater than or equal to the value returned by count), an NSRangeException is raised.
if this is only for debugging, you could try using po <> in the gdb.
As of clang version 3.3, you can use the [index] notation, so
NSString *str1 = array[0];
would work now. See here for details.
Related
What is the difference of notificationIdToCancle1 and notificationIdToCancle2 in the code below:
NSDictionary* parameters = (NSDictionary* )parametersObject;
if (parameters != nil) {
NSString* notificationIdToCancle1 = (NSString* )[parameters objectForKey:#"id"];
NSString *notificationIdToCancle2 = [NSString stringWithFormat:#"%#",[parameters valueForKey:#"id"]];
}
Shouldn't both contain the same value?
NSString* notificationIdToCancle1 = (NSString* )[parameters objectForKey:#"id"];
This line is grabbing the object in the dictionary, casting it to an NSString whether it is or isn't.
[NSString* stringWithFormat:#"%#",[parameters valueForKey:#"id"]];
This line, I think you have a mistake, you probably don't want the first '*'. You also probably want to call 'objectForKey:' rather than 'valueForKey:'. objectForKey: will return the entry in the dictionary, while valueForKey: will use Key Value Coding to return a value.
So:
[NSString stringWithFormat:#"%#",[parameters objectForKey:#"id"]];
This takes the object in the dictionary, runs 'description' on it which returns an NSString instance. So you definitely get an NSString instance out of it.
I have an NSArray, where each object contains a specific class called Card. Card has a description method. I want to join all objects in the array using the output of the description method, separated by spaces. Is there a simple to do this, without manually iterating the NSArray and manipulating NSString?
Something akin to the following made-up code?
NSArray *myArray = getCards(); // fetches 10 items or more
NSString *myString = [myArray joinUsingDescriptionMethodSeparatedBy:#" "];
or
NSString *myString = [NSString stringFromArrayDescriptionMethods:myArray separatedBy:#" "];
Naturally ,I could implement this myself but I suspect there could be something already present that does this.
I don't think that there is such a method. You can also implement it in a Category for NSString.
Sorry, I found this:
NSString * result = [[array valueForKey:#"description"] componentsJoinedByString:#""];
From the documentation:
Constructs and returns an NSString object that is the result of
interposing a given separator between the elements of the array.
- (NSString *)componentsJoinedByString:(NSString *)separator
Do this for description method of each NSArray item:
NSMutableString * result = [[NSMutableString alloc] init];
for (NSObject * obj in array)
{
[result appendString:[NSString stringWithFormat:#" %#"[obj description]]];
}
NSLog(#"The concatenated string is %#", result);
I am trying to split the string into parts and insert into a table how should i do it?
I got an error for splitting of the array which is: -[__NSArrayI componentsSeparatedByString:]: unrecognized selector sent to instance 0x7a421e0
NSArray *BusRoute = alightDesc;
int i;
int count = [BusRoute count];
for (i = 0; i < count; i++)
{
NSDictionary *dic = [BusRoute objectAtIndex: i];
NSDictionary *STEPS = [dic valueForKey:#"STEPS"];
NSString *AlightDesc = [STEPS valueForKey:#"AlightDesc"];
NSLog(#"AlightDesc = %#", AlightDesc);
NSArray *aDescArray = [AlightDesc componentsSeparatedByString:#","];
NSLog(#"aDescArray = %#", aDescArray);
}
This is the string which I'm splitting, i got it from the NSLog
AlightDesc = (
"Block1",
"Block2",
"Block3"
)
please help I'm stuck thanks.
Objective C is not a strongly typed language. All you know for sure about [STEPS valueForKey:#"AlightDesc"] is that it will return an object (of type id). When you wrote NSString *AlightDesc = [STEPS valueForKey:#"AlightDesc"] the compiler did not complain because NSString * is a valid object type. Unfortunately there is a logic error in your code so that what was actually stored under the key #"AlightDesc" is an NSArray. As others have mentioned, NSArray does not respond to componentsSeparatedByString: so you get an error at runtime.
The easy fix for this is to correct your logic: Either store an NSString in the first place or treat what you get out as an NSArray. As #janusfidel mentioned you can use an NSArray perfectly well in a table by using objectAtIndex: to get the string for the entry you want.
In some more complicated cases you may not know what you will be getting out of a dictionary for a particular key. In that case in Objective C you can just ask the object:
id anObject = [STEPS valueForKey:#"AlightDesc"];
if ([anObject isKindOfClass:[NSString class]]) {
NSString *aString = (NSString *)anObject;
// Treat as a string ...
} else if ([anObject isKindOfClass:[NSString class]]) {
// Object is an array ...
Your NSString *AlightDesc should look like this
NSString *AlightDesc = "Block1,Block2,Block3";
NSArray *aDescArray = [AlightDesc componentsSeparatedByString:#","];
If your string is what you say it is
AlightDesc = ("Block1","Block2","Block3");
then your string is the problem because it's already broken up.
i'm new to obj-c (this is my first day class eheh) and i'm trying to change a label with a random string from a multidimensional array. plus, every time the button is hitten you switch the array. i know it's a bit odd eheh… this is the IBAction:
UIButton *button = (UIButton *)sender;
NSMutableArray *firstArray = [NSMutableArray array];
[firstArray addObject:#"foo"];
NSMutableArray *secondArray = [NSMutableArray array];
[secondArray addObject:#"bar"];
NSMutableArray *frasi = [NSMutableArray array];
[frasi addObject:firstArray];
[frasi addObject:secondArray];
NSMutableArray *array = [NSMutableArray arrayWithObjects:[frasi objectAtIndex:[button isSelected]], nil];
NSString *q = [array objectAtIndex: (arc4random()% [array count] )];
NSString *lab = [NSString stringWithFormat:#"%#", q];
self.label.text = lab;
all works, but the new label is
( "foo" )
instead of just foo (without quotes)... probably i mess in the last block of code...
ty
So, you create 2 mutable arrays, then add them to a new mutable array frasi. Then you get one of those two arrays and use it as the single element (because you use arrayWithObjects: instead of arrayWithArray:) of a new array array.
So array is an array that contains a single array element (instead of an array of strings as you may believe).
When you get an object from array, it's always the same single object that was used to initialize it: either firstArray or secondArray.
So you get an array of strings where you expect a string. When using stringWithFormat:, the specifier %# is replaced with the string description of that object.
A string returns itself as its own description. But the description of an array is the list of all its elements separated with commas and surrounded by parenthesis, which is why you get ( "foo" ).
So instead or creating unneeded arrays, you may just replace all the 8th last lines with this:
NSArray *array = [button isSelected] ? secondArray : firstArray;
self.label.text = [array objectAtIndex:arc4_uniform([array count])];
Actually u have array within array
Replace this line with yours:
NSString *q = [[array objectAtIndex: (arc4random()% [array count] )] objectAtIndex:0];
I'm splitting a string by ';', but want to specifically grab the first and second element.
I know with PHP it's just simply $array[0], just can't find anything for this for Objective-C
NSArray *tempArray = [returnString componentsSeparatedByString:#";"];
So here I have assigned my array, how can I go about getting the first and second element?
Its just simply [array objectAtIndex:0] in Objective-C ;-)
Starting with XCode 4.5 (and Clang 3.3), you may use Objective-C Literals:
NSString *tmpString1 = tempArray[1];
NSString *tmpString = [tempArray objectAtIndex:0];
NSLog(#"String at index 0 = %#", tmpString);
NSString *tmpString1 = [tempArray objectAtIndex:1];
NSLog(#"String at index 1 = %#", tmpString1);
You may also wish to do an IF statement to check tmpArray actually contains objects in before attempting to grab its value...
e.g.
if ([tempArray count] >= 2) {
// do the above...
}