Unfortunately, we are not planning any further patch releases for versions older than 5.6.

However, as a workaround and only if you're not using AirPlay or Secondary Displays:

Modify the trampoline code generated for your project at 'Classes/Unity/DisplayManager.mm' to not add observers for 'UIScreenDidConnectNotification' and 'UIScreenDidDisconnectNotification'

So:

```
- (id)init
{
if( (self = [super init]) )
{
/* [[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(screenDidConnect:)
name:UIScreenDidConnectNotification
object:nil
];

[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(screenDidDisconnect:)
name:UIScreenDidDisconnectNotification
object:nil
];
*/
_displayConnection = [NSMapTable
mapTableWithKeyOptions:NSPointerFunctionsStrongMemory | NSPointerFunctionsObjectPointerPersonality
valueOptions:NSPointerFunctionsStrongMemory | NSPointerFunctionsObjectPointerPersonality
];

for(UIScreen* screen in [UIScreen screens])
[self registerScreen:screen];

_mainDisplay = self[[UIScreen mainScreen]];
}
return self;
}
```

You can also alter the installed Unity playback engine directly at 'Unity/PlaybackEngines/iOSSupport/Trampoline/Classes/Unity/DisplayManager.mm'

This should prevent the crash for 5.4.

4.7 Trampoline can be fixed in the same way or again via the playback engine at 'Unity.app/Contents/PlaybackEngines/iossupport/Trampoline/Classes/Unity' or the Windows equivalent.

The fix has been backported and will be in 5.6.5p3