iOS链式编程

iOS中关于链式编程最直接的参考框架就是自动布局的框Masonry,我们简单看一下它官方给出的例子:

UIEdgeInsets padding = UIEdgeInsetsMake(10, 10, 10, 10);

[view1 mas_makeConstraints:^(MASConstraintMaker *make) {
    make.top.equalTo(superview.mas_top).with.offset(padding.top); //with is an optional semantic filler
    make.left.equalTo(superview.mas_left).with.offset(padding.left);
    make.bottom.equalTo(superview.mas_bottom).with.offset(-padding.bottom);
    make.right.equalTo(superview.mas_right).with.offset(-padding.right);
}];

实现

关于链式编程的实现，个人觉得这篇文章已经写的很不错了谈谈 Objective-C 链式语法的实现就不赘述，引用了其中的一张调用图如下：

image

计算器例子

OC实现

首先封装计算器的类：

#import 

@interface XZCalculator : NSObject

@property (assign, nonatomic) NSInteger result;

- (XZCalculator *(^)(NSInteger num))add;

- (XZCalculator *(^)(NSInteger num))minus;

- (XZCalculator *(^)(NSInteger num))multiply;

- (XZCalculator *(^)(NSInteger num))divide;

@end

#import "XZCalculator.h"

@implementation XZCalculator

- (XZCalculator *(^)(NSInteger num))add{
    return ^(NSInteger num){
        _result += num;
        NSLog(@"result %d",_result);
        return self;
    };
}

- (XZCalculator *(^)(NSInteger num))minus{
    return ^(NSInteger num){
        _result -= num;
        NSLog(@"result %d",_result);
        return self;
    };
}


- (XZCalculator *(^)(NSInteger num))multiply{
    return ^(NSInteger num){
        _result *= num;
        NSLog(@"result %d",_result);
        return self;
    };
}


- (XZCalculator *(^)(NSInteger num))divide{
    return ^(NSInteger num){
        _result /= num;
        NSLog(@"result %d",_result);
        return self;
    };
}

@end

测试代码:

XZCalculator *calculator = [[XZCalculator alloc] init];
calculator.add(10).minus(5).multiply(3).divide(5);

执行结果

2017-11-07 10:05:07.123349+0800 CalculatorForOC[5815:231724] result 10
2017-11-07 10:05:07.123559+0800 CalculatorForOC[5815:231724] result 5
2017-11-07 10:05:07.123678+0800 CalculatorForOC[5815:231724] result 15
2017-11-07 10:05:07.123775+0800 CalculatorForOC[5815:231724] result 3

做一个NSObject的分类继续简化调用：

#import 
#import "XZCalculator.h"

@interface NSObject (XZCalculator)

- (void)xz_makeCalculation:(void(^)(XZCalculator *calculator))block;

@end

#import "NSObject+XZCalculator.h"

@implementation NSObject (XZCalculator)

- (void)xz_makeCalculation:(void(^)(XZCalculator *calculator))block{
    XZCalculator *calculator = [[XZCalculator alloc] init];
    block(calculator);
}
@end

测试代码:

[self xz_makeCalculation:^(XZCalculator *calculator) {
    calculator.add(10).minus(5).multiply(3).divide(5);
}];

执行结果:

2017-11-07 10:13:33.999146+0800 CalculatorForOC[6047:253166] result 10
2017-11-07 10:13:33.999304+0800 CalculatorForOC[6047:253166] result 5
2017-11-07 10:13:33.999405+0800 CalculatorForOC[6047:253166] result 15
2017-11-07 10:13:33.999497+0800 CalculatorForOC[6047:253166] result 3

Swift实现

swift中函数的调用方式就是使用.(参数)的方式，因此实现没必要使用OC中的闭包去实现，具体实现例子参考如下：

import UIKit

class XZCalculator: NSObject {
    
    var result:Int = 0;

    func add(_ num:Int) -> XZCalculator {
        self.result += num;
        print("result \(self.result)");
        return self;
    }
    
    func minus(_ num:Int) -> XZCalculator {
        self.result -= num;
        print("result \(self.result)");
        return self;
    }
    
    func multiply(_ num:Int) -> XZCalculator {
        self.result *= num;
        print("result \(self.result)");
        return self;
    }
    
    func divide(_ num:Int) -> XZCalculator {
        self.result /= num;
        print("result \(self.result)");
        return self;
    }
}

测试代码

let calculator:XZCalculator = XZCalculator();
calculator.add(10).minus(5).multiply(3).divide(5);

执行结果

result 10
result 5
result 15
result 3

同样我们做一个NSObject的扩展继续简化调用：

import Foundation

extension NSObject {
    func xz_makeCalculation(_ block:(_ calculator:XZCalculator) -> ()){
        let calculator:XZCalculator = XZCalculator();
        block(calculator);
    }
}

测试代码

self.xz_makeCalculation { (calculator:XZCalculator) in
    calculator.add(10).minus(5).multiply(3).divide(5);
};

执行结果

result 10
result 5
result 15
result 3

参考文章

• 谈谈 Objective-C 链式语法的实现