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 <Foundation/Foundation.h>
@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 <Foundation/Foundation.h>
#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
