macOS about memory managing--dealloc & autorelease

//  Controller.h

#import <Cocoa/Cocoa.h>


@interface Controller : NSObject {
    IBOutlet NSImageView *imageView;
    NSMutableArray * images;
    int currentImage;
}
- (IBAction)nextImage:(id)sender;

@end

//  Controller.m

#import "Controller.h"

@implementation Controller

- (void)awakeFromNib
{
    NSBundle * mainBundle = [NSBundle mainBundle];
    NSArray * imagePaths = [mainBundle pathsForResourcesOfType:@"jpg"
												   inDirectory:nil];
    images = [[NSMutableArray alloc] init];
    int count = [imagePaths count];
    int i;
    for (i = 0; i < count; i++) {
        NSImage * image = [[NSImage alloc] initWithContentsOfFile:
						   [imagePaths objectAtIndex:i]];
        [images addObject:image];
        [image release];
    }
    currentImage = 0;
    [imageView setImage:[images objectAtIndex:currentImage]];
}

- (IBAction)nextImage:(id)sender
{
    currentImage++;
    if (currentImage == [images count]) {                              // a
        currentImage = 0;
    }
    [imageView setImage:[images objectAtIndex:currentImage]];          // b
}

@end