关于代码风格的一些见解(二)
接上一篇文章说到使用ViewModel来瘦身ViewController,也就是把ViewController中有关原始数据适配到view需要的数据的一种办法.
- (void)onRoomInfoUpdateNotification:(NSNotification*)notification
{
MFChatRoomMessage* message = [[MFChatRoomMessage alloc] init];
message.msgType = kSystemType;
message.msgSubType = kPlanTextSubType;
MFRoomInfo* roomInfo = [[MFAppModel sharedObject].chatroomModelEx getCurrentRoomInfo];
NSNumber* isLock = [[notification userInfo] objectForKey:KChatRoomIsLockChangeKey];
NSNumber* isTopicChange = [[notification userInfo] objectForKey:KChatRoomIsTopicChangeKey];
if (isLock.unsignedIntegerValue == 1) {
message.msgText = (roomInfo.locked ? @"房主将房间锁定" : @"房主将房间解锁了");
} else if (isTopicChange.unsignedIntegerValue == 1) {
message.msgText = [NSString stringWithFormat:@"房主更改了话题 %@", roomInfo.subject];
} else {
message.msgText = @"房主更改了房间信息";
}
[self appendChatRoomMessage:message forceRefresh:YES];
}
截取上面一段代码仅供参考说明,这段代码实际上就干了一件事:
[self appendChatRoomMessage:message forceRefresh:YES];
把message传给appendChatRoomMessage进行后续的处理,而上面的若干行代码都是对message进行赋值,那最简单的想法就是能否通过一个方法可以直接获取到message,有了这样的想法,我们会定义这样的方法
+ (MFChatRoomMessage *)getChatRoomMessage:(NSNotification*)notification msgType:(MFChatRoomMsgType)msgType msgSubType:(MFChatRoomMsgSubType)msgSubType {
MFChatRoomMessage* message = [[MFChatRoomMessage alloc] init];
message.msgType = kSystemType;
message.msgSubType = kPlanTextSubType;
MFRoomInfo* roomInfo = [[MFAppModel sharedObject].chatroomModelEx getCurrentRoomInfo];
NSNumber* isLock = [[notification userInfo] objectForKey:KChatRoomIsLockChangeKey];
NSNumber* isTopicChange = [[notification userInfo] objectForKey:KChatRoomIsTopicChangeKey];
if (isLock.unsignedIntegerValue == 1) {
message.msgText = (roomInfo.locked ? @"房主将房间锁定" : @"房主将房间解锁了");
} else if (isTopicChange.unsignedIntegerValue == 1) {
message.msgText = [NSString stringWithFormat:@"房主更改了话题 %@", roomInfo.subject];
} else {
message.msgText = @"房主更改了房间信息";
}
return message;
}
那记下来ViewController里面只需要写
- (void)onRoomInfoUpdateNotification:(NSNotification*)notification
{
MFChatRoomMessage* message = [MyViewModel getChatRoomMessage:notification msgType:kSystemType msgSubType:kPlanTextSubType];
[self appendChatRoomMessage:message forceRefresh:YES];
}
这样就只要在VC里写两句话,而构造message的细节都封装在ViewModel里.
我们可能有很多像onRoomInfoUpdateNotification这样的回调,最终都要转换成MFChatRoomMessage, 那既然这类notification的作用只是对数据进行处理,和UI并没半毛钱关系,那就可以直接把这些全都封装到ViewModel里.接下来再看下我们的appendChatRoomMessage里面到底要干什么
- (void)appendChatRoomMessage:(MFChatRoomMessage *)message forceRefresh:(BOOL)forceRefresh
{
[_msgArray addObject:message];
if (_msgArray.count > 50) {
[_msgArray removeObjectAtIndex:0];
}
if (forceRefresh) {
[self reloadAllMessage];
return;
}
}
把数据message加到一个数组,然后刷新UI,所以我们最终的目的还是刷UI,那实际上我们的ViewController连msgArray都不需要了,只要持有ViewModel就可以了
所以综上所述,MyViewModel应该是类似这样的
@interface MyViewModel : NSObject @property (nonatomic, strong) NSMutableArray *msgArray; - (void)addChatRoomMessage:(NSNotification*)notification msgType:(MFChatRoomMsgType)msgType msgSubType:(MFChatRoomMsgSubType)msgSubType; @end
@implementation
- (NSMutableArray *)msgArray {
if(_msgArray == nil) {
_msgArray = [NSMutableArray array];
}
return _msgArray;
}
- (MFChatRoomMessage *)getChatRoomMessage:(NSNotification*)notification msgType:(MFChatRoomMsgType)msgType msgSubType:(MFChatRoomMsgSubType)msgSubType {
MFChatRoomMessage* message = [[MFChatRoomMessage alloc] init];
message.msgType = kSystemType;
message.msgSubType = kPlanTextSubType;
MFRoomInfo* roomInfo = [[MFAppModel sharedObject].chatroomModelEx getCurrentRoomInfo];
NSNumber* isLock = [[notification userInfo] objectForKey:KChatRoomIsLockChangeKey];
NSNumber* isTopicChange = [[notification userInfo] objectForKey:KChatRoomIsTopicChangeKey];
if (isLock.unsignedIntegerValue == 1) {
message.msgText = (roomInfo.locked ? @"房主将房间锁定" : @"房主将房间解锁了");
} else if (isTopicChange.unsignedIntegerValue == 1) {
message.msgText = [NSString stringWithFormat:@"房主更改了话题 %@", roomInfo.subject];
} else {
message.msgText = @"房主更改了房间信息";
}
return message;
}
- (void)addChatRoomMessage:(NSNotification*)notification msgType:(MFChatRoomMsgType)msgType msgSubType:(MFChatRoomMsgSubType)msgSubType {
MFChatRoomMessage * message = [self getChatRoomMessage:notification msgType:msgType msgSubType:msgSubType];
[self.msgArray addObject:message];
}
@end
然后在MyViewController里
@interface MyViewController : UIViewController @property (nonatomic, strong) MyViewModel *viewModel; @end
@implementation MyViewController
- (MyViewModel *)viewModel {
if(_viewModel == nil) {
_viewModel = [[MyViewModel alloc] init];
}
return _viewModel;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
return self.viewModel.msgArray[indexPath.row];
}
- (void)onRoomInfoUpdateNotification:(NSNotification*)notification {
[self.viewModel addChatRoomMessage:notification msgType:kSystemType msgSubType:kPlanTextSubType];
[self.tableView reload];
}
@end
这里就进行了近一步的封装,把和数据msgArray的操作细节都封装到了VM,VC完全不用进行复杂的数据处理工作了.同样的想法,如果一个VC里面同一个table有很多Cell,也同样可以封装进VM,而VC只关心最后得到的cell,这样做会减少VC的大小,而可以更容易看明白VC的控制细节,而VM作为一个数据的转化工厂被VC持有,VC可以方便的取出View需要的最终数据.