[Objective-C] Builder Design Pattern

Builder

// Builder.h

#import <Foundation/Foundation.h>

@interface ObjectBuilder : NSObject

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSNumber *age;

@end

@interface Builder : NSObject

@property (nonatomic, copy, readonly) NSString *name;
@property (nonatomic, copy, readonly) NSNumber *age;

- (instancetype)init;
- (instancetype)initWithBuilder:(ObjectBuilder *)builder;
+ (instancetype)makeWithBuilder:(void (^)(ObjectBuilder *))updateBlock;
- (instancetype)update:(void (^)(ObjectBuilder *))updateBlock;

@end

// Builder.m

#import "Builder.h"

@implementation ObjectBuilder

- (instancetype)init
{
    if (self = [super init])
    {
        _name = nil;
        _age = nil;
    }
    
    return self;
}

@end

@implementation Builder

- (instancetype)initWithBuilder:(ObjectBuilder *)builder
{
    if (self = [super init])
    {
        _name = builder.name;
        _age = builder.age;
    }
    
    return self;
}

- (ObjectBuilder *)makeBuilder
{
    ObjectBuilder *builder = [ObjectBuilder new];
    builder.name = _name;
    builder.age = _age;
    
    return builder;
}

- (instancetype)init
{
    ObjectBuilder *builder = [ObjectBuilder new];
    
    return [self initWithBuilder:builder];
}

+ (instancetype)makeWithBuilder:(void (^)(ObjectBuilder *))updateBlock
{
    ObjectBuilder *builder = [ObjectBuilder new];
    updateBlock(builder);
    
    return [[Builder alloc] initWithBuilder:builder];
}

- (instancetype)update:(void (^)(ObjectBuilder *))updateBlock
{
    ObjectBuilder *builder = [self makeBuilder];
    updateBlock(builder);
    
    return [[Builder alloc] initWithBuilder:builder];
}

@end

// Example

Builder *builder = [Builder makeWithBuilder:^(ObjectBuilder *builder)
{
    builder.name = @"Max";
    builder.age = @23;
}];

NSLog(@"%@", builder.name);

Builder *updatedBuilder = [builder update:^(ObjectBuilder *builder)
{
    builder.name = @"Maxim";
}];

NSLog(@"%@", updatedBuilder.name);