Populate NSTableView with a new object by clicking a button - objective-c

Question

Im trying to populate an NSTableView with a custom object by clicking a button. My custom class has just NSString properties: title and volume. I customized the init method to create an object and add it to my array that is hooked up to my table view. Then on the method for my button I had it create another object and add it to the array. When I run the program the object from the init method does display correctly. However, when I click my button I get nothing.
Here is the code for my header file:
#import <Cocoa/Cocoa.h>
#interface AppDelegate : NSObject <NSApplicationDelegate, NSTableViewDataSource>{
NSMutableArray *_myArray;}
#property (weak) IBOutlet NSTableView *tableView;
- (IBAction)button:(id)sender;
#end
and here is my implementation:
#import "AppDelegate.h"
#import "trade.h"
#interface AppDelegate ()
#property (weak) IBOutlet NSWindow *window;
#end
#implementation AppDelegate
-(id)init{
self = [super init];
if (self){
_myArray = [[NSMutableArray alloc]init];
trade *firstTrade = [[trade alloc]init];
[firstTrade setTitle:#"Trade One"];
[firstTrade setVolume:#"Volume 01"];
[_myArray addObject:firstTrade];}
return self;}
- (IBAction)button:(id)sender {
trade *secondTrade = [[trade alloc]init];
[secondTrade setTitle:#"Trade two"];
[secondTrade setVolume:#"Volume 02"];
[_myArray addObject:secondTrade];
[_tableView reloadData];}
-(NSInteger)numberOfRowsInTableView:(NSTableView *)tableView{
return _myArray.count;}
-(id)tableView:(NSTableView *)tableView objectValueForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row{
if ([tableColumn.identifier isEqualToString:#"Title"]){
trade *item = [_myArray objectAtIndex:row];
return item.title;
}else{
trade *item = [_myArray objectAtIndex:row];
return item.volume;}}
#end
Not sure what I'm doing wrong here as what I did in the init method is pretty much the same thing I did in button method. Any help is greatly appreciated. Here is a picture of the program after I run it:
tableView program
As you can see my first object appears in the table view, but not the second.
While looking at this project I duplicated the [_tableView reloadData]; line and placed a breakpoint on the second one so I could see what was going on right after the first one is called. One thing I noticed is that _myArray does now contain 2 objects after the button click.
However, when I look into _tableView it shows that _myArray only contains 1 object. How is it that the object is actually getting added but the table view is only getting 1?
Here is a picture for reference:Debug