i've set some preferences in my app as strings: #"YES" and #"OFF" for #"Active" and #"Enabled", tried to set them upon launch in
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions"
as
NSDictionary *udd = [NSDictionary dictionaryWithObject:#"YES" forKey:#"Active"];
[NSDictionary dictionaryWithObject:#"OFF" forKey:#"Enabled"];
[[NSUserDefaults standardUserDefaults] registerDefaults:udd];
but i can only see the first string returned which is the "YES" for
NSLog(#"%#",[udd objectForKey:#"Active"]);
not
NSLog(#"%#",[udd objectForKey:#"Enabled"]);
which returns a "null".
I'm a bit stuck how to add more strings to udd for my preferences? Can anybody advise?
Many thanks in advance.
Jon.
x = y; z; is not what you want (it doesn't set x twice, and it definitely doesn't set x to some sort of combined value). You probably to make a single dictionary and set that, rather than two dictionaries and throw the second one away.
Related
I have two text fields and user entered the values. I can get the values of textFields like below
NSString *number1 = firstTextField.text;
NSString *number2 = secondTextField.text;
I want to multiply number1 and number2 without converting them into integer or number.I am doing like below
NSExpression *expression = [NSExpression expressionWithFormat:[NSString stringWithFormat:#"%#*%#",number1,number2]];NSLog(#"Multiplication result is----%#",[expression expressionValueWithObject:nil context:nil]);
I don't know if it is correct or not. If it is not correct please give me the suggestions how it can be possible.
By using NSExpression is one way to Multiply/Add/Subtract two number strings without converting them into integer or number.
NSExpression *expression = [NSExpression expressionWithFormat:expressionFormat];
You are using here expressionFormat as [NSString stringWithFormat:#"%#*%#",number1,number2];.
If you want to add or subtract number1 and number2 then replace * with + or -. In this way you have to proceed.
If the question was in an interview.
The interviewers were probably expecting you to write a method to go through both arrays and multiply the characters (converting one by one to integers) or (also identifying the represented character to know the equivalent integer number).
Searching on google there are some examples in different languages.
JAVA
http://csjobinterview.wordpress.com/2012/04/05/string-multiplication/
string multiplication
C++
Multiplying two number arrays
It is a common question in interviews.
I simply used textfields... and used the values that the user input into those textfields... here is one calculation example that has worked for me... in this example the user is trying to find the volume of beachstone they would need to order... the formula is pretty straight forward. Make sure you use the math brackets () to distinguish order of operations...
-(IBAction)calculate_beachstone:(id)sender {
float floatanswer =
([area1.text floatValue])+([area2.text floatValue])+([area3.text floatValue])+([area4.text floatValue])+([area5.text floatValue])+([area6.text floatValue])+([area7.text floatValue])+([area8.text floatValue])+([area9.text floatValue])+([area10.text floatValue]))
*([beachstone_depth.text floatValue])/12)/27);
NSString *stringRectResult=[[NSString alloc]
initWithFormat:#"%.1f",floatanswer];
answer_beachstone.text=stringRectResult;
}
I am adding the text found in the textfield (which user can only use numbers for input - custom keyboard)... in this example I have up to 10 fields which can be added together... then I use the * (multiply) to apply a depth in this example, and convert it back to a text string so I can display the result somewhere else...
In fact, if you write this part answer_beachstone to NSUserDefaults, you can use the result anywhere in different controllers, by calling it back.
If you're interested, here is how I did that...
-(IBAction)save_answer_beachstone:(id)sender {
save_answer_beachstone = [[NSString alloc] initWithString:answer_beachstone.text];
[answer_beachstone setText:save_answer_beachstone];
NSUserDefaults *save = [NSUserDefaults standardUserDefaults];
[save setObject:save_answer_beachstone forKey:#"save_answer_beachstone"];
}
Then I can use the resulting "answer" in any controller inside viewDidLoad...
[answer_beachstone setText:[[NSUserDefaults standardUserDefaults] objectForKey:#"save_answer_beachstone"]];
I know the question was asked 4 years ago, but this formula syntax works for me in a number of ways, in various apps...
You can't multiply two strings. It's not possible.
For this you have to convert it into Integer or int using NSNumber or using:
[secondTextField.text intValue].
NSInteger number = [firstTextField.text integerValue]*[secondTextField.text integerValue];
Something weird just happened.
I stored a NSNumber with an unsigned long long value in NSUserDefaults. When I retrieve it, the value just changed. It seems that system thinks the number is long long instead of unsigned long long.
What's worse is that when I compare the number retrieved from UserDefaults with the original number, the result is NotEqual!
what's wrong with the code? Thank you!
static NSString * const NumberKey = #"MyNumber";
unsigned long long value = 15908045869032883218ULL;
if ([[NSUserDefaults standardUserDefaults] objectForKey:NumberKey] == nil) {
NSNumber *number = [NSNumber numberWithUnsignedLongLong:value];
[[NSUserDefaults standardUserDefaults] setObject:number forKey:NumberKey];
NSLog(#"Original Number:%#", number); // 15908045869032883218, right
}
NSNumber *number = [[NSUserDefaults standardUserDefaults] objectForKey:NumberKey];
NSLog(#"Current Number:%#", number); // -2538698204676668398, weird
NSLog(#"Current Value:%llu", [number unsignedLongLongValue]); // 15908045869032883218, right
NSLog(#"%d", [number isEqualToNumber:[NSNumber numberWithUnsignedLongLong:value]]); // 0
NSLog(#"%d", [number unsignedLongLongValue] == value); // 1
To further answer your question. If you look in the documentation for NSNumber's isEqualToNumber: function you will notice the following line,
Two NSNumber objects are considered equal if they have the same id values or if they have equivalent values
it's important you understand this. In your code you are asking is my NSNumber object "number" equal to "value", you are not asking does the numerical value stored within my NSNumber object "number" equal the numerical value stored within my NSNumber object "value".
The last line of code you have written shows that in fact your NSNumber's numerical values are in fact equal.
NSLog(#"%d", [number unsignedLongLongValue] == value); //1
So you are correctly storing and retrieving the values, you should be using the == comparison method with NSNumber objects stored numerical values (ie intValue == intValue, unsignedLongLongValue == unsignedLongLongValue) and not comparing their object id's together.
As for this line of code
NSLog(#"Current Number:%#", number); // -2538698204676668398, weird
This is not weird, this is perfectly normal, as you have told NSLog to print out an NSObject representation of 'number'. I'm not 100% certain but I believe that NSNumber's - ( NSString * ) description function defaults to return an unsigned int value for the numerical value it contains. This is why you are getting the large negative number returned. You may want to look at NSNumber's - (NSString *)descriptionWithLocale:(id)aLocale function to print out the data in a more logical for for you, or you could use
NSLog(#"Current Number:%llu", [number unsignedLongLongValue]);
Which will give you the right answer.
EDIT:
Further to this, after looking into the issue what is happening is that on recollection of your NSNumber object from UserDefaults it's original number type is not being preserved (this information is highlighted in the documentation for NSNumber in the overview section)
(Note that number objects do not necessarily preserve the type they are created with.)
You can see this yourself if you log the following after retrieving "number" from user defaults (add this to the end of the code you have in your question) and have a look at the encoding values shown here
NSLog(#"%s", [number objCType]); //This will log out q
NSLog(#"%s", [[NSNumber numberWithUnsignedLongLong:value] objCType]); //this will log out Q
The difference between Q and q is that Q is an unsigned value... hence why you are having issues with the isEqualToNumber: function as the number types are different.
If you are so dead set on using the iSEqualToNumber: function to compare values then you could implement this to retrieve your value from NSUserDefaults.
NSNumber *number = [NSNumber numberWithUnsignedLongLong:[[NSUserDefaults standardUserDefaults] objectForKey:NumberKey] unsignedLongLongValue]];
You could look at using the NSNumber compare: function to see if the returned value is NSOrderedSame however this will not work for comparing unsigned vs signed values of the same type so in your situation I'd use the above as retrieving the data from NSUserDefaults is stripping the "signedness" of your number.
At the end of the day if you want to store NSNumber into NSUserDefaults this code works for me even for large integers like: 881217446193276338
To save:
[[NSUserDefaults standardUserDefaults] setObject:self.myUser.sessionid forKey:#"sessionid"];
[[NSUserDefaults standardUserDefaults] synchronize];
To recover:
self.myUser.sessionid = (NSNumber *)[[NSUserDefaults standardUserDefaults] objectForKey:#"sessionid"];
It's storing it correctly, nothing is wrong with your code except:
NSLog(#"Current Number:%#", number);
Here number is a non-string object, you might think of it as a wrapper for a numerical primitive. Or you might think that NSNumber instances objectify a primitive type.
What you need is some thing like:
NSLog(#"Current Number:%#", [number stringValue]);
Here is a speculative answer:
The NSNumber documentation states that:
(Note that number objects do not necessarily preserve the type they are created with.) .
So it must be using a different internal storage for this type, and only gives you the correct value when you specifically ask for the unsigned long long value. The description method, which is called in your NSLog statement, may be defaulting to a different representation type.
And / or there may be some quirk of the unarchiver that is preventing the isEqualToNumber method working on the value returned from defaults. If you do that comparison between two NSNumbers created in the same scope, does it work? The correct value is definitely in there somewhere given your last statement returns true.
I'm sure this is a very obvious question but I'm not getting anywhere with it and I've been trying for half an hour or so now.
I have an NSMutableDictionary which has keys & values, obviously. Each key stores an array of objects. What I need to do is find a specific array in a key and get the list of the array. The catch is that I don't know the value of the key, I just know it's index. (EG: I know I need to find the array in the 2nd key).
I am almost certain this is a very easy & trivial thing to do but it's escaping me, I've only been doing Obj-C for a short while so not entirely at home with it yet!
Thanks,
Jack.
Use allKeys: to access the keys of your dictionary.
- (NSArray *)allKeys
Use as below .
NSArray* dictAllKeys = [dict allKeys];
if([dictAllKeys count] > 2)
{
NSArray* myArrayInDict = [dict objectForKey:[dictAllKeys objectAtIndex:1]];
// get the length of array in dict at 2nd key
int length = [myArrayInDict count];
}
The order will probably change if another key/value pair is added, it is a NSMutableDictionary. It is best not to rely on the order of a NSDictionary or NSSet.
Suggestion: Either use another container that does provide ordering such as NSMutableArray or find the item using the dictionary's value arrays, perhaps with NSPredicate.
The problem is when de selectedSegmentIndex is unselected: "UISegmentedControlNoSegment" alias "-1".
The other states (0, 1, 2 , etc.), I can store as Integers and retrieve with
carTypeSegmentedControl.selectedSegmentIndex = [defaults integerForKey:#"typeOfCar"];
But -1 is no NSInteger.
I also tried to remove the Integer out of the NSUserdefaults but a request would return an "0", which is not acceptable.
So, is there another easy way?
-1 is an integer, it's a negative integer. You should be able to store this in NSUserDefaults.
You need to use NSNumber, which is an object representation of values of common numerical and boolean types, e.g. to set:
[[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithInt:-1] forKey:kDefaultCarSegmentedControlState];
To retrieve:
NSInteger defaultCarSegmentedControlSelectedIndex = [[[NSUserDefaults standardUserDefaults] objectForKey:kDefaultCarSegmentedControlState] intValue];
You are right Ben, -1 is indead an integer. And it is stored after all. I did an NSLog on that. Stupid i didn't try that. I didn't find clear documentation on that.
So probably my problem is somewhere els.
I guess your answer works as well, Alex.
Thank you for helping
I've got an NSDictionary that was initialized with a plist that, among other things, contained count followed by 32 and I want to get at the value for count.
How?
I know how to get it into an object via
[dictionaryObjectName objectForKey:#"count"]
But to me, the value I'm obtaining is not an object.
If I have to specify an object, what would be the best one to use (FYI the value will always be unsigned) and I need to get it into a true int.
Do I do something like
NSNumber *num = [dictionaryObjectName objectForKey:#"count"];
int theValue = [num intValue];
[num release];
Is the release on num a good thing to do since this for an iPhone with no garbage collector?
And nicer form is:
int theValue = [[dictionaryObjectName objectForKey:#"count"] intValue];
EDIT
Since I see that people still arrive to this page, let's clarify that these days you simply do
int theValue = [dictionaryObjectName[#"count"] intValue];
Yes, you pull it out as an NSNumber, then grab the int(eger)Value but there's no need to release it. You didn't retain, alloc, or copy the number, so you don't have to worry about releasing it.