鏈?zhǔn)秸{(diào)用也是所謂的鏈?zhǔn)骄幊坦保窃贛asonry中寫法看起來十分直觀，調(diào)用起來也很簡(jiǎn)單耀销。在特定的應(yīng)用環(huán)境下利用block實(shí)現(xiàn)鏈?zhǔn)骄幊萄郑_實(shí)會(huì)大大的使代碼直觀易讀。

[_contentView addSubview:_imgView];   
[_imgView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.leading.equalTo(@(20));
        make.top.equalTo(@(20));
        make.bottom.equalTo(@(-20));
        make.height.equalTo(@(CellHeight - 40));
        make.width.equalTo(self.imgView.frame.height);
}];

1. 方法的通常調(diào)用過程

// Animal.h 中定義
- (void)eat;
- (void)sleep;

// Animal.m 中實(shí)現(xiàn)
- (void)eat {
    NSLog(@"%s", __FUNCTION__);
}
- (void)sleep {
    NSLog(@"%s", __FUNCTION__);
}

// 通常調(diào)用過程
Animal *animal = [[Person alloc] init];
[animal sleep];
[animal eat];

2. 普通的鏈?zhǔn)秸{(diào)用

普通的鏈?zhǔn)秸{(diào)用就是我們常見的树姨，多個(gè)[ ]方法調(diào)用嵌套在一起摩桶，達(dá)到鏈?zhǔn)秸{(diào)用的效果，還是比較好理解帽揪，也比較常用硝清。

// Animal.h 中定義
- (Animal *)eat;
- (Animal *)sleep;

// Animal.m 中實(shí)現(xiàn)
- (Animal *)eat {
    NSLog(@"%s", __FUNCTION__);
    return self;
}
- (Animal *)sleep {
    NSLog(@"%s", __FUNCTION__);
    return self;
}

// 鏈?zhǔn)秸{(diào)用
[[animal eat] sleep];
//[[animal sleep] eat];

3. 用block實(shí)現(xiàn)鏈?zhǔn)秸{(diào)用

如下定義相當(dāng)于直接使用block變量的get方法：

// Animal.h 中定義
- (void (^)())eat;
- (void (^)())sleep;

// Animal.m 中實(shí)現(xiàn)
- (void (^)())eat {
    void (^eatBlock)() = ^ {
        NSLog(@"%s", __FUNCTION__);
    };
    return eatBlock;
}
- (void (^)())sleep {
    return ^ {
        NSLog(@"%s", __FUNCTION__);
    };
}

// 調(diào)用
animal.eat();
animal.sleep();

則，block的鏈?zhǔn)秸{(diào)用

// Animal.h  中定義
- (Animal * (^)(NSString *foodName))eat;
- (Animal * (^)(NSInteger hour))sleep;

// Animal.m 中實(shí)現(xiàn)
- (Animal *(^)(NSString *))eat {
    Animal * (^eatBlock)() = ^(NSString *foodName) {
        NSLog(@"吃: %@", foodName);
        return self;
    };
    return eatBlock;
}
- (Animal *(^)(NSInteger))sleep {
    return ^(NSInteger hour) {
        NSLog(@"睡%ld", (long)hour);
        return self;
    };
}

// 鏈?zhǔn)秸{(diào)用
animal.eat(@"蛋糕").sleep(8);
animal.sleep(8).eat(@"面包");

4. 請(qǐng)實(shí)現(xiàn)一個(gè)例子

我們創(chuàng)建一個(gè)view转晰，平常初始化時(shí)會(huì)直接調(diào)用其.frame芦拿、.backgroundColor等方法設(shè)置樣式。大家可以試著使用鏈?zhǔn)骄幊谭绞綄?shí)現(xiàn)以下功能：

CustomView *custom = [CustomView makeCustomView:^(CustomView *custom) {
        custom.viewFrame(CGRectMake(50, 50, 200, 200)).viewColor([UIColor cyanColor]);
}];
[self.view addSubview:custom];