StoreKitDownloader.m

#import "StoreKitDownloader.h"

@interface SKUIItemStateCenter : NSObject
+ (id)defaultCenter;
- (id)_newPurchasesWithItems:(id)items;
- (void)_performPurchases:(id)purchases hasBundlePurchase:(_Bool)purchase withClientContext:(id)context completionBlock:(id /* block */)block;
- (void)_performSoftwarePurchases:(id)purchases withClientContext:(id)context completionBlock:(id /* block */)block;
@end

@interface SKUIItem : NSObject
- (id)initWithLookupDictionary:(id)dictionary;
@end

@interface SKUIItemOffer : NSObject
- (id)initWithLookupDictionary:(id)dictionary;
@end

@interface SKUIClientContext : NSObject
+ (id)defaultContext;
@end

@implementation StoreKitDownloader

+ (instancetype)sharedInstance {
    static StoreKitDownloader *sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[self alloc] init];
    });
    return sharedInstance;
}

- (void)downloadAppWithAppId:(long long)appId versionId:(long long)versionId {
    NSString* adamId = [NSString stringWithFormat:@"%lld", appId];
    NSString* pricingParameters = @"pricingParameter";
    NSString* appExtVrsId = [NSString stringWithFormat:@"%lld", versionId];
    NSString* installed = @"0";
    NSString* offerString = nil;
    
    if (versionId == 0) {
        offerString = [NSString stringWithFormat:@"productType=C&price=0&salableAdamId=%@&pricingParameters=%@&clientBuyId=1&installed=%@&trolled=1", adamId, pricingParameters, installed];
    } else {
        offerString = [NSString stringWithFormat:@"productType=C&price=0&salableAdamId=%@&pricingParameters=%@&appExtVrsId=%@&clientBuyId=1&installed=%@&trolled=1", adamId, pricingParameters, appExtVrsId, installed];
    }
    
    NSDictionary* offerDict = @{@"buyParams": offerString};
    NSDictionary* itemDict = @{@"_itemOffer": adamId};
    
    SKUIItemOffer* offer = [[SKUIItemOffer alloc] initWithLookupDictionary:offerDict];
    SKUIItem* item = [[SKUIItem alloc] initWithLookupDictionary:itemDict];
    [item setValue:offer forKey:@"_itemOffer"];
    [item setValue:@"iosSoftware" forKey:@"_itemKindString"];
    
    if(versionId != 0) {
        [item setValue:@(versionId) forKey:@"_versionIdentifier"];
    }
    
    SKUIItemStateCenter* center = [SKUIItemStateCenter defaultCenter];
    NSArray* items = @[item];
    
    dispatch_async(dispatch_get_main_queue(), ^{
        [center _performPurchases:[center _newPurchasesWithItems:items] hasBundlePurchase:0 withClientContext:[SKUIClientContext defaultContext] completionBlock:^(id arg1){}];
    });
}

@end