MVVM模式將Presenter改名為ViewModel,基本上與MVP模式完全一致。

唯一的區別是，它采用雙向綁定(data-binding) : View<->ViewModel, ViewModel作為Model中值的映射，是數據發生改變時，通知View中發生改變，以后不需要考慮View和Model之間的交互更新，只需著手界面布局邏輯即可。

①View和Model 不直接關聯，而是通過ViewModel作為樞紐，溝通View和Model之間的關系。

②View中控件的值與屬性進行綁定，通過KVO鍵值觀察(這樣當model的值發生變化時,View會自動發生改變)?

View和Model通過ViewModel實現動態關聯。

1.MVVModel代碼

#import <Foundation/Foundation.h> @interface MVVMModel : NSObject @property(nonatomic,copy)NSString *name; @end

2.MVVMViewModel代碼

MVVMViewModel.h

#import <Foundation/Foundation.h> #import "MVVMModel.h" @interface MVVMViewModel : NSObject @property(nonatomic,copy)NSString *nameStr; @property(nonatomic,strong)MVVMModel *model;-(void)setWithModel:(MVVMModel *)model; -(void)clickChangeName; @end

MVVMViewModel.m

#import "MVVMViewModel.h"@implementation MVVMViewModel -(instancetype)init{if (self = [super init]) {}return self; }-(void)setWithModel:(MVVMModel *)model{self.model = model;self.nameStr = model.name; } -(void)clickChangeName{self.model.name = [NSString stringWithFormat:@"name%d",arc4random()%10];self.nameStr = self.model.name;NSLog(@"%@",self.nameStr); } @end

3.MVVMView代碼

#import <UIKit/UIKit.h> #import "MVVMViewModel.h" @interface MVVMView : UIView -(void)setWithViewModel:(MVVMViewModel *)vm; @end#import "MVVMView.h" @interface MVVMView ()@property(nonatomic,strong)MVVMViewModel *vm; @property(nonatomic,strong)UILabel *label; @property(nonatomic,strong)UIButton *button;@end @implementation MVVMView- (instancetype)init {self = [super init];if (self) {self.backgroundColor = [UIColor whiteColor];self.frame = [UIScreen mainScreen].bounds;self.label = [[UILabel alloc]initWithFrame:CGRectMake(150,100 , 100, 30)];self.label.backgroundColor = [UIColor orangeColor];[self addSubview:_label];self.button = [UIButton new];_button.backgroundColor = [UIColor redColor];[_button setTitle:@"點擊" forState:UIControlStateNormal];[_button addTarget:self action:@selector(mvvmClickChangModel) forControlEvents:UIControlEventTouchUpInside];_button.frame = CGRectMake(150, 200, 50, 50);[self addSubview:_button];}return self; } - (void)setWithViewModel:(MVVMViewModel *)vm {self.vm = vm;//KVO[self.vm addObserver:self forKeyPath:@"nameStr" options:NSKeyValueObservingOptionOld|NSKeyValueObservingOptionNew context:nil];self.label.text = vm.nameStr;}-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change: (NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{if ([keyPath isEqualToString:@"nameStr"]&&[change objectForKey:NSKeyValueChangeNewKey]) {NSNumber *new = [change objectForKey:NSKeyValueChangeNewKey];self.label.text = [NSString stringWithFormat:@"%@",new];} } -(void)mvvmClickChangModel{[self.vm clickChangeName]; }-(void)dealloc{[self.vm removeObserver:self forKeyPath:@"nameStr"]; } @end

3.ViewController.m

#import "ViewController.h" #import "MVVMView.h" #import "MVVMModel.h" #import "MVVMViewModel.h"@interface ViewController () @property (nonatomic, strong) MVVMViewModel * viewModel ; @end@implementation ViewController - (void)viewDidLoad {[super viewDidLoad];MVVMView *MView = [MVVMView new];MVVMModel *model = [MVVMModel new];model.name = @"name1";MVVMViewModel *viewModel = [MVVMViewModel new];[self.view addSubview:MView];//*viewModel 作為樞紐 溝通view和model之間關系 [viewModel setWithModel:model];[MView setWithViewModel:viewModel]; } @end

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轉載于:https://www.cnblogs.com/StevenHuSir/p/AppArchitecture_MVVM.html

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