我正在重新设计应用程序并正在重构和扩展我的模型。
我的应用模型的一个方面是应用从Web服务检索数据并填充模型。
我的问题是：我的模型对象是否应该具有实现NSURLSession的能力，还是应该依靠VC来提供连接？
我从最佳实践角度提出要求。考虑这个问题的最佳方式是什么？该模型应完全独立还是应该具有网络访问权限？
一个考虑因素是，如果没有来自网络的数据，这些模型对象基本上是无用的，这意味着来自互联网的数据是其存在的一个基本方面。
答案 0 :(得分：3)
如果我们考虑SOLID - 尤其是Single Responsible Principle的S - ，很明显，VC和模型都不应该进行联网：
这三点将实现SOLID，但是如何将网络中的数据转换为模型对象显示在视图上？
嗯，这取决于您在应用程序上的整体架构设计，但常见的方法是使用回调 - 委托协议或块 - 与您的网络控制器。
您可以在应用程序委托中创建网络控制器，并将其从视图控制器传递到视图控制器，通过属性到应用程序中的任何位置都需要新获取的数据。我不会在这里使用单身，因为这违反了O，I＆amp;固体D
将类方法添加到模型+(NSArray *)modelObjectsFromDictionaries:(NSArray *)或类似方法中
在视图控制器中，您现在可以执行
-(void)viewDidLoad
{
[super viewDidLoad];
__weak typeof(self) weakSelf = self;
[self.networkController fetchModels:^(NSArray *modelDictionaries, NSError *error){
typeof(weakSelf) self = weakSelf;
if(self) {
if(!error){
[self.dataSource addOrUpdateData:[Model modelObjectsFromDictionaries:modelDictionaries]];
} else {
// error handling
}
}
}];
}
这只是一个起点。对于更复杂的API，使用自身使用网络控制器和可能是持久性控制器的api控制器可能很有用。
虽然您可能想要使用某种映射和抽象工厂模式而不是Model类方法......但是所有这些都需要有关您的应用的更多信息，并且不在此问题的范围内。
更新
我创建了一个示例项目来证明这一点
它与我上面说的略有不同：
因为它使用表视图，我使用数据源类来填充它。数据源将告诉网络控制器获取新数据，而不是视图控制器。
我正在使用OFAPopulator，这是我编写的库，以符合SOLID的方式填充表视图和集合视图，或者“保持视图控制器清洁和MVC智能”。
#import "AppDelegate.h"
#import "VSNetworkController.h"
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[self.window.rootViewController setValue:[[VSNetworkController alloc] initWithBaseURL:[NSURL URLWithString:@"http://api.goeuro.com/api/v2/"]]
forKey:@"networkController"];
return YES;
}
@end
// VSNetworkController.h
#import <Foundation/Foundation.h>
@interface VSNetworkController : NSObject
-(instancetype)initWithBaseURL:(NSURL *) baseURL;
-(void)suggestionsForString:(NSString *)suggestionString
responseHandler:(void(^)(id responseObj, NSError *error))responseHandler;
@end
// VSNetworkController.m
#import "VSNetworkController.h"
@interface VSNetworkController ()
@property (nonatomic, strong) NSURL *baseURL;
@end
@implementation VSNetworkController
-(instancetype)initWithBaseURL:(NSURL *)baseURL
{
self = [super init];
if (self) {
_baseURL = baseURL;
}
return self;
}
-(void)suggestionsForString:(NSString *)suggestionString
responseHandler:(void(^)(id responseObj, NSError *error))responseHandler
{
NSURL *url = [self.baseURL URLByAppendingPathComponent:[NSString stringWithFormat:@"position/suggest/en/%@", suggestionString]];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data,
NSError *connectionError) {
responseHandler([NSJSONSerialization JSONObjectWithData:data options:0 error:nil], connectionError);
}];
}
@end
// VSLocationSuggestion.h
#import <Foundation/Foundation.h>
@import CoreLocation;
@interface VSLocationSuggestion : NSObject
@property (nonatomic, copy, readonly) NSString *name;
@property (nonatomic, copy, readonly) NSString *country;
@property (nonatomic, strong, readonly) CLLocation *position;
+(NSArray *)suggestionsFromDictionaries:(NSArray *)dictionaries;
@end
// VSLocationSuggestion.m
#import "VSLocationSuggestion.h"
@interface VSLocationSuggestion ()
@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *country;
@property (nonatomic, strong) CLLocation *position;
@end
@implementation VSLocationSuggestion
+(NSArray *)suggestionsFromDictionaries:(NSArray *)dictionaries
{
NSMutableArray *array = [@[] mutableCopy];
[dictionaries enumerateObjectsUsingBlock:^(NSDictionary *suggestionDict, NSUInteger idx, BOOL *stop) {
[array addObject:[[self alloc] initWithDictionary:suggestionDict]];
}];
return [array copy];
}
-(instancetype)initWithDictionary:(NSDictionary *)dict
{
self = [super init];
if (self) {
_name = dict[@"name"];
_country = dict[@"country"];
CLLocationDegrees latitude = [dict[@"geo_position"][@"latitude"] doubleValue];
CLLocationDegrees longitude =[dict[@"geo_position"][@"longitude"] doubleValue];
_position = [[CLLocation alloc] initWithLatitude:latitude longitude:longitude];
}
return self;
}
@end
// VSSuggestionDataSource.h
#import <Foundation/Foundation.h>
#import <OFADataProvider.h>
@class VSNetworkController;
@interface VSSuggestionDataSource : NSObject <OFADataProvider>
-(instancetype)initWithNetworkController:(VSNetworkController *)networkController;
-(void)setNewSuggestions:(NSArray *)suggetsions;
-(void)enteredStringForSuggestions:(NSString *)suggestionString;
@end
// VSSuggestionDataSource.m
#import "VSSuggestionDataSource.h"
#import "VSNetworkController.h"
#import "VSLocationSuggestion.h"
@interface VSSuggestionDataSource ()
@property (nonatomic, copy) void (^available)(void);
@property (nonatomic, strong) VSNetworkController *networkController;
@end
@implementation VSSuggestionDataSource
@synthesize sectionObjects;
-(instancetype)initWithNetworkController:(VSNetworkController *)networkController
{
self = [super init];
if (self) {
_networkController = networkController;
}
return self;
}
-(void)dataAvailable:(void (^)(void))available
{
_available = available;
}
-(void)setNewSuggestions:(NSArray *)suggetsions
{
self.sectionObjects = suggetsions;
self.available();
}
-(void)enteredStringForSuggestions:(NSString *)s
{
__weak typeof(self) weakSelf = self;
[self.networkController suggestionsForString:s responseHandler:^(NSArray *responseObj, NSError *error) {
typeof(weakSelf) self = weakSelf;
if (self) {
if (!error && responseObj) {
NSArray *suggestion = [VSLocationSuggestion suggestionsFromDictionaries:responseObj];
[self setNewSuggestions:suggestion];
}
}
}];
}
@end
// ViewController.h
#import <UIKit/UIKit.h>
@class VSNetworkController;
@interface ViewController : UIViewController
@property (nonatomic, strong) VSNetworkController *networkController;
@end
// ViewController.m
#import "ViewController.h"
#import "VSLocationSuggestion.h"
#import <OFAViewPopulator.h>
#import <OFASectionPopulator.h>
#import "VSSuggestionDataSource.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UITableView *tableView;
@property (strong, nonatomic) OFAViewPopulator *viewPopultor;
@property (strong, nonatomic) VSSuggestionDataSource *dataSource;
- (IBAction)textChanged:(UITextField *)sender;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.dataSource = [[VSSuggestionDataSource alloc] initWithNetworkController:self.networkController];
OFASectionPopulator *sectionPopulator = [[OFASectionPopulator alloc] initWithParentView:self.tableView
dataProvider:self.dataSource
cellIdentifier:^NSString *(id obj, NSIndexPath *indexPath) {
return @"Cell";
} cellConfigurator:^(VSLocationSuggestion *obj, UITableViewCell *cell, NSIndexPath *indexPath) {
cell.textLabel.text = obj.name;
}];
sectionPopulator.objectOnCellSelected = ^(VSLocationSuggestion *suggestion, UIView *cell, NSIndexPath *indexPath ){
NSString * string =[NSString stringWithFormat:@"%@, %@ (%f %f)", suggestion.name, suggestion.country, suggestion.position.coordinate.latitude, suggestion.position.coordinate.longitude];
UIAlertController *avc = [UIAlertController alertControllerWithTitle:@"Selected" message:string preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *cancelAction = [UIAlertAction
actionWithTitle:NSLocalizedString(@"Cancel", @"Cancel action")
style:UIAlertActionStyleCancel
handler:^(UIAlertAction *action)
{
;
}];
[avc addAction:cancelAction];
[self presentViewController:avc animated:YES completion:NULL];
};
self.viewPopultor = [[OFAViewPopulator alloc] initWithSectionPopulators:@[sectionPopulator]];
}
- (IBAction)textChanged:(UITextField *)sender
{
NSString *s = sender.text;
if ([s length]) {
[self.dataSource enteredStringForSuggestions:s];
}
}
@end;
我在github上提供了这段代码：https://github.com/vikingosegundo/LocationSugesstion