A picky array to satisfy Loyal

LYLPickyArray.h

//
//  LYLPickyArray.h
//
//  Copyright (c) 2015 NYTimes. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface LYLPickyArray : NSMutableArray

- (instancetype)initWithClass:(Class)requiredClass predicate:(NSPredicate *)predicate;

@end

LYLPickyArray.m

//
//  LYLPickyArray.m
//
//  Copyright (c) 2015 NYTimes. All rights reserved.
//

#import "LYLPickyArray.h"

@interface LYLPickyArray() {
    Class _requiredClass;
    NSPredicate *_predicate;
}

@end

@implementation LYLPickyArray

- (instancetype)initWithClass:(Class)requiredClass predicate:(NSPredicate *)predicate {
    self = [super init];

    if (self) {
        if (requiredClass) {
            NSPredicate *classPredicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
                return [evaluatedObject isKindOfClass:requiredClass];
            }];

            if (predicate) {
                _predicate = [NSCompoundPredicate andPredicateWithSubpredicates:@[classPredicate, predicate]];
            }
            else {
                _predicate = classPredicate;
            }
        }
        else if (predicate) {
            _predicate = predicate;
        }
        else {
            _predicate = [NSPredicate predicateWithValue:YES];
        }
    }

    return self;
}

- (void)addObject:(id)anObject {
    if ([_predicate evaluateWithObject:anObject]) {
        [super addObject:anObject];
    }
    else {
        NSAssert(NO, @"Invalid object type");
    }
}

@end