iOS开发之设计模式 - 简单工厂模式

简单工厂模式

• 简单工厂模式， 解决对象的创建问题，工厂本身包括了多有的方法集合

实现计算器部分功能

swift

import Foundation

// 计算的根类
class Operation: NSObject {
    
    var numberA: Double?
    var numberB: Double?
    
    public func getResult() -> Double {
        let result: Double  = 0
        return result
    }
}

// 计算符操作类
class OperationAdd: Operation {
    
    override func getResult() -> Double {
        var result = 0.0
        result = numberA! + numberB!
        return result
    }
}

class OperationMulyi: Operation {
    
    override func getResult() -> Double {
        var result = 0.0
        result = numberA! * numberB!
        return result
    }
}
/**
 .
 . 多种运算类
 .
 **/

// 简单工厂模式
class OperationFactory: NSObject {
    
    class func createOperate(operate: String) -> Operation
    {
        var oper = Operation()
        
        switch operate {
        case "+":
            oper = OperationAdd()
        case "*":
            oper = OperationMulyi()
        default:
            break
        }
        
        return oper
    }
}

// 计算
var op = Operation()
op = OperationFactory.createOperate(operate: "+")
op.numberA = 1.0
op.numberB = 2.0
let result = op.getResult()

OC

#import "ViewController.h"

@interface ViewController ()

@end


// 基类
@interface Operation : NSObject
@property (nonatomic, assign, readwrite) double numberA;
@property (nonatomic, assign, readwrite) double numberB;
@property (nonatomic, assign, readwrite) double result;
- (double)getResult;
@end

@implementation Operation

@end


// 子类 +
@interface  OperationAdd : Operation
@end

@implementation OperationAdd // 加

- (double)getResult
{
    double result = 0;
    result = self.numberA + self.numberB;
    return result;
}

@end

@interface OperationSub: Operation

@end

// 子类 -
@implementation OperationSub // 减法

- (double)getResult
{
    double result = 0;
    result = self.numberB - self.numberA;
    return result;
}

@end


// 工厂类
@interface OperationFactory : NSObject
+ (Operation *)createOperate:(NSString *)operate1;
@end

@implementation OperationFactory

+ (Operation *)createOperate:(NSString *)operate1 {
    Operation *operation = [[Operation alloc] init];
    if ([operate1 isEqualToString:@"+"]) {
        operation = [[OperationAdd alloc] init];
    } else {
        operation = [[OperationSub alloc] init];
    }
    return operation;
}
@end



@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    Operation *oper = [Operation new];
    oper = [OperationFactory createOperate:@"+"];
    oper.numberB = 1;
    oper.numberA = 2;
    double result = oper.getResult;
    
    NSLog(@"和为 = %f", result);
    
}

@end

想一下如果这样写代码， 我们又要加上一些其他的操作符，这样仅仅在创建一个类，继承一下Operation，在工厂里面添加一行代码 即可简单创建了， 今后想一下我们是否需要抽出一个抽象类来进行实体运算！

反思， 如果是项目中， 如何用简单工厂模式？

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