I would like to assign NSInteger by using NSMutableArray is there any way to solve this?
It is not working on simulator and cut off when run the application.
NSInteger Section;
NSMutableArray dataSourceSection;
Section = (NSInteger)[dataSourceSection objectAtIndex:2];
Thank you.
A NSMutableArray only stores objects. NSInteger is not an object, but a primitive data type. There is a class NSNumber, however, that can be used instead to store numeric values inside objects. Here's one example.
NSNumber *five = [NSNumber numberWithInteger:5];
NSMutableArray *numbers = [NSMutableArray array];
[numbers addObject:five];
To get the object back and retrieve the integer value use,
NSNumber *firstNumber = [numbers objectAtIndex:0];
NSInteger valueOfFirstNumber = [firstNumber integerValue];
you can't pull an NSInteger out of an NSMutableArray, basically because you can't put anything rather than objects in. in your case NSNumber would be the way to put numbers in NSMutablearray. if you do so you can easily get hold of your object, which is an NSNumber, and convert it to a NSInteger by:
NSMutableArray *array = [[NSMutableArray alloc] init];
// populate the array with NSNumbers
NSInteger number = [[array objectAtIndex:2] intValue];
Related
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];
Is there something like NSMutableArray that will take doubles directly without putting them inside the #""?
You can only put objects into an NSMutableArray. But you can wrap your doubles in NSNumber like so:
NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:0];
[array addObject:[NSNumber numberWithDouble:0.12345]];
[array addObject:[NSNumber numberWithDouble:5.43210]];
You can only insert objects into an NSMutableArray. Luckily, there is a class, NSNumber, that is used to wrap Objective-C primitives as objects. You can use the doubleValue method to get your primitive value back.
For example:
NSMutableArray *numArray = [[NSMutableArray alloc]initWithObjects:[NSNumber numberWithDouble:1.1f], nil];
double num = [[numArray objectAtIndex:0]doubleValue];
I'm writing an app for iPhone in objective-c. I want to declare an array that will hold different type of fields , like: int, NSString, bool.
Can I do it?
You can put whatever items in an NSArray as long as they are objects. So you have to wrap items that are not objects (such as BOOL, int and CGPoint) in some kind of objects such as NSNumber or NSValue.
NSMutableArray *array = [[NSMutableArray] alloc] init];
[array addObject:myString];
[array addObject:[NSNumber numberWithInt:1]];
[array addObject:[NSNumber numberWithFloat:1.0]];
[array addObject:[NSValue valueWithPoint:myPoint]]; // myPoint is a CGPoint
[array addObject:[NSValue valueWithRect:myRect]]; // myRect is a CGRect
Yes, you can
NSMutableArray *array = [NSMutableArray array];
NSString *string = #"str";
[array addObject:string]; //string
NSNumber *num = [NSNumber numberWithInt:1];
[array addObject:num]; //int
NSNumber *boolNum = [NSNumber numberWithBool:YES];
[array addObject:boolNum]; //bool
Use NSMutableArray.
NSMutableArray *array = [[NSMutableArray alloc]init];
Now use addObject: method to add objects. for adding int, bool value create NSNumber object.
It is possible. Just create the array and add the objects you want added.
I want to make a float value array. How can I do this? My code is:
NSArray *tmpValue = [[NSArray alloc] init];
total = total + ([[self.closeData objectAtIndex:i]floatValue] - total)* expCarpan;
firstValue = total;
NSArrays only take object types. You can add various non-object types to an NSArray by using the NSNumber wrapper:
NSNumber *floatNumber = [NSNumber numberWithFloat:myFloat];
[myArray addObject:floatNumber]; // Assuming `myArray` is mutable.
And then to retrieve that float from the array:
NSNumber *floatNumber = [myArray objectAtIndex:i];
float myFloat = [floatNumber floatValue];
(As you have done in your code above).
Update:
You can also use the NSValue wrapper in the same way as NSNumber for other non-object types, including CGPoint/Size/Rect/AffineTransform, UIOffset/EdgeInsets and various AV Foundation types. Or you could use it to store pointers or arbitrary bytes of data.
The NSArray class can only contain instances of other Objective-C objects. Fortunately, Apple already has several Objective-C object types for encapsulating C primitive types. For instance, NSNumber can incapsulate many different types of C numbers (integers, floats, etc.). NSValue can incapsulate arbitrary structures, CGPoints, pointers, etc. So, you can use NSNumber and float in conjunction with NSArray as follows:
NSArray * myArray;
NSNumber * myFloatObj = [NSNumber numberWithFloat:3.14];
myArray = [NSArray arrayWithObjects:myFloatObj, nil];
You can then get the original float value from the first NSNumber of the array:
NSNumber * theNumber = [myArray objectAtIndex:0];
float theFloat = [theNumber floatValue];
Alternatively, you can turn this into a one-liner:
float theFloat = [[myArray objectAtIndex:0] floatValue];
Primitive types can't be included in a NSArray, which is only for objects. For numbers, use NSNumber to wrap your floats.
NSNumber *n1 = [NSNumber numberWithFloat:1.2f];
NSNumber *n2 = [NSNumber numberWithFloat:1.4f];
NSArray *array = [NSArray arrayWithObjects:n1, n2, nil];
I am trying to create an NSArray of bool values. How many I do this please?
NSArray *array = [[NSArray alloc] init];
array[0] = YES;
this does not work for me.
Thanks
NSArrays are not c-arrays. You cant access the values of an NSArray with array[foo];
But you can use c type arrays inside objective-C without problems.
The Objective-C approach would be:
NSMutableArray *array = [[NSMutableArray alloc] init];
[array addObject:[NSNumber numberWithBool:YES]];
//or
[array addObject:#(NO)];
...
BOOL b = [[array objectAtIndex:0] boolValue];
....
[array release];
EDIT: New versions of clang, the now standard compiler for objective-c, understand Object subscripting. When you use a new version of clang you will be able to use array[0] = #YES
Seems like you've confused c array with objc NSArray. NSArray is more like a list in Java, into which you can add objects, but not values like NSInteger, BOOL, double etc. If you wish to store such values in an NSArray, you first need to create a mutable array:
NSMutableArray* array = [[NSMutableArray alloc] init];
And then add proper object to it (in this case we'll use NSNumber to store your BOOL value):
[array addObject:[NSNumber numberWithBool:yourBoolValue]];
And that's pretty much it! If you wish to access the bool value, just call:
BOOL yourBoolValue = [[array objectAtIndex:0] boolValue];
Cheers,
Pawel
Use [NSNumber numberWithBool: YES] to get an object you can put in the collection.