Nullability and Inheritance

TMObjectThatHasLotsOfDependenciesInjected.h

@interface TMObjectThatHasLotsOfDependenciesInjected : NSObject

- (nonnull instancetype)initWithDependency:(TMDependency * __nonnull)dependency
                         anotherDependency:(TMOtherDependency * __nonnull)anotherDependency NS_DESIGNATED_INITIALIZER;
                         
/// option 1: break inheritance
- (nullable instancetype)init __attribute__((unavailable("Use initWithDependency:anotherDependency: instead")));

@end

TMObjectThatHasLotsOfDependenciesInjected.m

@implementation TMObjectThatHasLotsOfDependenciesInjected

- (instancetype)initWithDependency:(TMDependency *)dependency
                 anotherDependency:(TMOtherDependency *)anotherDependency {
  NSParameterAssert(dependency);
  NSParameterAssert(anotherDependency);
  
  self = [super init];
  if (self) {
    // ...
  }
  
  return self;
}

/// option 2: break nullability and crash at runtime because of parameter asserts
- (instancetype)init {
  return [self initWithDependency:nil anotherDependency:nil];  // passing nil to nonnull arguments
}