Avoid push_back

Avoid doing this:

std::vector<CKFlexboxComponentChild> children;
if (someSetting) {
  children.push_back({[HeaderComponent newWithModel:model});
}
if (fooComponent) {
  children.push_back({fooComponent});
}
return [super newWithComponent:
        [CKFlexboxComponent
         newWithView:{}
         size:{}
         style:{}
         children:children]];

There are a few reasons why:

• There are good reasons to avoid mutable local variables in general.
• nil children are automatically dropped by CKFlexboxComponent, so there's no need to check for nil before adding to the list of children.
• Conditionals are best done inline; or, encapsulate the checks in a new CKCompositeComponent that renders to nil if the conditional fails.

Instead, do this:

return [super newWithComponent:
        [CKFlexboxComponent
         newWithView:{}
         size:{}
         style:{}
         children:{
           {someSetting ? [HeaderComponent newWithModel:model] : nil},
           {fooComponent},
         }]];