如何在 Objective-C 中创建字符串或浮点数组

Question

i need some help here, i need to know how to create an array of string retrieved from an array. i'm using powerplot for graph and it only accept float or string array.

i need to create something something like this dynamically.

NSString * sourceData[7] = {@"2", @"1", @"4", @"8", @"14", @"15", @"10"};

Below are my code to find out the numbers in strings.

NSInteger drunked = [appDelegate.drinksOnDayArray count];
NSMutableArray * dayArray = [[NSMutableArray alloc] init];
NSMutableArray * sdArray = [[NSMutableArray alloc] init];
//float *sdArray[7];


for (int i=0; i<drunked; i++) {
    DayOfDrinks *drinksOnDay = [appDelegate.drinksOnDayArray objectAtIndex:i];
    NSString * dayString= [NSDate stringForDisplayFromDateForChart:drinksOnDay.dateConsumed];
    [dayArray addObject:dayString];
    NSLog(@"%@",[dayArray objectAtIndex:i]);

    drinksOnDay.isDetailViewHydrated = NO;
    [drinksOnDay hydrateDetailViewData];

    NSString * sdString= [NSString stringWithFormat:@"%@", drinksOnDay.standardDrinks];
    [sdArray addObject:sdString];

    NSString *tempstring;
    NSLog(@"%@",[sdArray objectAtIndex:i]);

}

thanks for the help:)

Answer 1

Array's in Objectice-C aren't that hard to work with:

NSMutableArray *myArray = [NSMutableArray array];
[myArray addObject:@"first string"]; // same with float values
[myArray addObject:@"second string"];
[myArray addObject:@"third string"];
int i;
int count;
for (i = 0, count = [myArray count]; i < count; i = i + 1)
{
   NSString *element = [myArray objectAtIndex:i];
   NSLog(@"The element at index %d in the array is: %@", i, element); // just replace the %@ by %d
}

You can either use NSArray or NSMutableArray - depending on your needs, they offer different functionality.

Following tutorial covers exactly what you are looking after:

http://www.cocoalab.com/?q=node/19

Answer 2

You can also add the elements to the array when you init (and optionally add them later only if you are using the Mutable version of a collection class:

NSMutableArray *myArray = [[NSMutableArray alloc] initWithObjects:@"2", @"1", @"4", @"8", @"14", @"15", @"10", nil];
[myArray addObject:@"22"];
[myArray addObject:@"50"];

//do something

[myArray release];

Answer 3

You can use malloc to create a C-style array. something like this should work:

NSString **array = malloc(numElements * sizeof(NSString *))
some code here
free(array)

Be aware that unlike NSMutable array, c arrays won't do a retain, so you have to manage it if needed. And don't forget the free