RaceCondition2

StackTrace.txt

Thread 5Queue : com.apple.root.user-initiated-qos (concurrent)
#0	0x000000010f181d2b in objc_release ()
#1	0x000000010f1831d1 in (anonymous namespace)::AutoreleasePoolPage::pop(void*) ()
#2	0x00000001125037ce in _dispatch_root_queue_drain ()
#3	0x0000000112503059 in _dispatch_worker_thread3 ()
#4	0x00000001128cb4de in _pthread_wqthread ()
#5	0x00000001128c9341 in start_wqthread ()

StringContainer.h

#import <Foundation/Foundation.h>

@interface StringContainer : NSObject

@property (nonatomic, strong) NSString *string;
- (instancetype)initWithString:(NSString *)string;

@end

StringContainer.m

#import "StringContainer.h"

@implementation StringContainer

- (instancetype)initWithString:(NSString *)string {
    self = [super init];
    if (self) {
        self.string = string;
    }
    return self;
}

@end

Test.h

#import <Foundation/Foundation.h>

@class StringContainer;

@interface Test : NSObject

@property (nonatomic, strong) StringContainer *stringProp;
    
@end

Test.m

#import "Test.h"
#import "StringContainer.h"

@interface Test() {
    StringContainer *_stringProp;
}

@end

@implementation Test

- (void)setStringProp:(StringContainer *)stringProp {
    [_stringProp autorelease];
    _stringProp = [stringProp retain];
}

- (StringContainer *)stringProp {
    return _stringProp;
}

@end

ViewController.m

@interface ViewController ()

@property (nonatomic, strong) Test *test;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self testCrash];
    // Do any additional setup after loading the view, typically from a nib.
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)testCrash {
    self.test = [Test new];
    for(int i = 0; i < 1000; i++) {
        dispatch_async(dispatch_get_global_queue(0, 0), ^() {
            self.test.stringProp = [[StringContainer alloc] initWithString:[[NSString alloc] initWithFormat:@"%d", i]];
        });
        dispatch_async(dispatch_get_global_queue(0, 0), ^() {
            [self print:self.test.stringProp];
        });
    }
}

- (void)print:(StringContainer * __unsafe_unretained)string {
    NSLog(@"%@", string.string);
}

@end