As per references like this or this, I take that iPhone 7 Plus on landscape should have regular size class.
This is the code in the current view controller, as per this reference:
- (void) traitCollectionDidChange: (UITraitCollection *) previousTraitCollection {
[super traitCollectionDidChange: previousTraitCollection];
NSLog(@"current trait collection: %@",self.traitCollection);
NSLog(@"previous trait collection: %@", previousTraitCollection);
}
And this is the output on the console when going from portrait to landscape on iPhone 7 Plus:
current trait collection: <UITraitCollection: 0x1c44efd00; _UITraitNameUserInterfaceIdiom = Phone, _UITraitNameDisplayScale = 3.000000, _UITraitNameDisplayGamut = P3, _UITraitNameHorizontalSizeClass = Compact, _UITraitNameVerticalSizeClass = Compact, _UITraitNameTouchLevel = 0, _UITraitNameInteractionModel = 1, _UITraitNameUserInterfaceStyle = 1, _UITraitNameUserInterfaceLayoutDirection = 0, _UITraitNameForceTouchCapability = 2, _UITraitNamePreferredContentSizeCategory = UICTContentSizeCategoryL, _UITraitNameDisplayCornerRadius = 0.000000>
previous trait collection: <UITraitCollection: 0x1c02fa900; _UITraitNameUserInterfaceIdiom = Phone, _UITraitNameDisplayScale = 3.000000, _UITraitNameDisplayGamut = P3, _UITraitNameHorizontalSizeClass = Compact, _UITraitNameVerticalSizeClass = Regular, _UITraitNameTouchLevel = 0, _UITraitNameInteractionModel = 1, _UITraitNameUserInterfaceStyle = 1, _UITraitNameUserInterfaceLayoutDirection = 0, _UITraitNameForceTouchCapability = 2, _UITraitNamePreferredContentSizeCategory = UICTContentSizeCategoryL, _UITraitNameDisplayCornerRadius = 0.000000>
The horizontal size class remains compact and I expected change from compact to regular.
Using iOS 11.1.2 and Xcode 9.1
Do you have display zoom turned on for the device?
https://help.apple.com/iphone/11/#/iphd6804774e
In "Standard" mode, the horizontal size class in landscape will be Regular. In "Zoomed" mode, it will be Compact.