Custom UIView causes a EXC_BAD_ACCESS code = 1 in layoutSubviews

Question

I have created a custom UIView which is instantiated 3 times from UIViewController. From the viewDidLoad method of that UIViewController:

self.remainingDays = [[RemainingTileView alloc] initWithFrame:CGRectMake(20, 49, 80, 75)];
self.remainingHours = [[RemainingTileView alloc] initWithFrame:CGRectMake(120, 49, 80, 75)];
self.remainingMinutes = [[RemainingTileView alloc] initWithFrame:CGRectMake(220, 49, 80, 75)];

[self.view addSubview:self.remainingDays];
[self.view addSubview:self.remainingHours];
[self.view addSubview:self.remainingMinutes];

In the RemainingTileView class, I have this layoutSubviews method:

- (void)layoutSubviews {
    [super layoutSubviews];

    if (self.number)    // This is an NSNumber property
        self.numberLabel = [self labelForNumber:[self.number intValue]];
    else
        self.numberLabel = [self labelForNumber:0];

    if (self.unit)    // This is an NSString property
        self.unitLabel = [self labelForUnit:self.unit];
    else
        self.unitLabel = [self labelForUnit:@""];

    [self configView];
}

When creating the view, it crashes on the line if (self.number) with the stack frame:

* thread #1: tid = 0x2403, 0x39f6c526 libobjc.A.dylib`objc_retain + 6, stop reason = EXC_BAD_ACCESS (code=1, address=0x10000010)
frame #0: 0x39f6c526 libobjc.A.dylib`objc_retain + 6
frame #1: 0x000dc742 myProject`-[RemainingTileView layoutSubviews](self=0x1e892b80, _cmd=0x344cde51) + 106 at RemainingTileView.m:63
frame #2: 0x3405d802 UIKit`-[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 258
frame #3: 0x33e07d8a QuartzCore`-[CALayer layoutSublayers] + 214
frame #4: 0x33e07928 QuartzCore`CA::Layer::layout_if_needed(CA::Transaction*) + 460
frame #5: 0x33e0885c QuartzCore`CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 16
frame #6: 0x33e08242 QuartzCore`CA::Context::commit_transaction(CA::Transaction*) + 238
frame #7: 0x33e08050 QuartzCore`CA::Transaction::commit() + 316
frame #8: 0x33e07eb0 QuartzCore`CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 60
frame #9: 0x322276cc CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 20
frame #10: 0x322259c0 CoreFoundation`__CFRunLoopDoObservers + 276
frame #11: 0x32225d16 CoreFoundation`__CFRunLoopRun + 742
frame #12: 0x32198ebc CoreFoundation`CFRunLoopRunSpecific + 356
frame #13: 0x32198d48 CoreFoundation`CFRunLoopRunInMode + 104
frame #14: 0x35d6f2ea GraphicsServices`GSEventRunModal + 74
frame #15: 0x340ae300 UIKit`UIApplicationMain + 1120
frame #16: 0x000d3448 Project Countdown`main(argc=1, argv=0x2fd2ecf8) + 116 at main.m:17

self.number is an instance of NSNumber. The UI is being modified from the main thread. I have looked for existings solutions here on stackoverflow but nothing worked.

What am I missing? What should I look for?

Answer 1

Looks like your properties have incorrect declarations. Probably assign or weak instead of retain, copy, or strong.

Answer 2

It looks like the property is returning some invalid object and ARC is attempting to retain it, which then fails. It looks like you might be better off moving your check for nil values into a custom property accessor, something along the lines of:

- (NSNumber *)number {
    if (_number == nil) {
        _number = [NSNumber numberWithInt:0];
    }
    return _number;
}

Then you can simply set the numberLabel value to number without having to check here. You can do something similar for unit as well.