将浮点值赋给NSMutableArray

Question

I want to assign float variables to nsmutable array in a for loop. I did it like below. But the nsmutable array is seems null. How can I solve this? (distance is float and enyakinarray is NSMutablearray.)

for (int i=0; i<[ws3.CustomerID count]; i++) {

    //radian hesaplaması
    float total = [first floatValue];
    float theta = total * M_PI/180;
    float total2 = [second floatValue];
    float theta2 = total2 * M_PI/180;
    float total3 = [[ws3.Latitude objectAtIndex: i]  floatValue];
    float theta3 = total3 * M_PI/180;
    float total4 = [[ws3.Longitude objectAtIndex: i] floatValue];
    float theta4 = total4 * M_PI/180;


     distance = 6371 * acos(cos(theta) * cos(theta3)
                           * cos(theta4 - theta2)
                           + sin(theta) * sin( theta3)) ;

    NSLog(@"xxxxx %f",distance);

    num = [NSNumber numberWithFloat:distance];
    enyakinarray = [[NSMutableArray alloc] init];
    [enyakinarray  addObject:num];
    NSLog(@"asasasas %@",enyakinarray);

}

Answer 1

Adding a number to an array NSArray (NSMutableArray) doesnt allow you to add primitive types to it. This is because an NSArray is simple a set of pointers to the Objects you add to it. This means if you want to add a number to the array, you first have to wrap it in a NSNumber .

NSArray *numbers=[NSArray arrayWithObject:[NSNumber numberWithInteger:2]];

Number type conversion

NSNumber allows you to easily convert the type of a number eg from an int to a float

NSNumber *number=[NSNumber numberWithInteger:2];
float floatValue = [number floatValue];

Answer 2

If the array is null (nil) then maybe you haven't initialised it?

enyakinarray = [[NSMutableArray alloc] init];

Don't forget if you alloc it, you need to release it when finished with it.

[enyakinarray release];

Answer 3

You are creating a new array every iteration of the for loop. You want to do this:

NSMutableArray *enyakinarray = [[NSMutableArray alloc] init];
for (int i=0; i<[ws3.CustomerID count]; i++) {

    //radian hesaplaması
    float total = [first floatValue];
    float theta = total * M_PI/180;
    float total2 = [second floatValue];
    float theta2 = total2 * M_PI/180;
    float total3 = [[ws3.Latitude objectAtIndex: i]  floatValue];
    float theta3 = total3 * M_PI/180;
    float total4 = [[ws3.Longitude objectAtIndex: i] floatValue];
    float theta4 = total4 * M_PI/180;


     distance = 6371 * acos(cos(theta) * cos(theta3)
                           * cos(theta4 - theta2)
                           + sin(theta) * sin( theta3)) ;

    NSLog(@"xxxxx %f",distance);

    num = [NSNumber numberWithFloat:distance];
    [enyakinarray  addObject:num];

}
NSLog(@"asasasas %@",enyakinarray);

Answer 4

Use CGFloat instead, I know that works. Also, I was reminded of something because of the comment below mine. NSNumber will work too, here is the class reference http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsnumber_Class/Reference/Reference.html