函数式编程思想：把操作尽可能的写成一系列的函数嵌套或者方法调用；

• 函数式编程本质：就是往方法中传入block，方法中嵌套block调用，把代码集合起来管理
• 函数式编程特点：每个方法必须有返回值（返回对象自身），把函数或者block当做参数；block的参数==需要操作的值（传参），block返回值==操作结果（返回值）

#import <Foundation/Foundation.h>

@interface CalculateManager : NSObject

@property (nonatomic, assign) int result;

- (instancetype)calculate:(int(^)(int))calculateBlock;
@end

#import "CalculateManager.h"

@implementation CalculateManager

- (instancetype)calculate:(int (^)(int))calculateBlock {
   _result = calculateBlock(_result);
    return self;
}
@end
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- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    CalculateManager *mgr = [[CalculateManager alloc] init];
    int res = [[mgr calculate:^int(int result) {
        result += 5;
        result *= 5;
        return result;
    }] result];

    NSLog(@"%i",res);
}