括号语法代码抽取

形式

int c = ({
代码行1;
代码行2;
c;
});
c的值由最后一行代码决定

int c = ({
    int a = 1;
    int b = 2;
    int c = a + b;
    c;
});

    //流水布局:调整cell尺寸
    UICollectionViewFlowLayout *layout = ({
        
        UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
        layout.itemSize = CGSizeMake(160, 160);
        //设置最小行间距
        layout.minimumLineSpacing = 50;
        layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
        CGFloat margin = (ScreenW - 160) * 0.5;
        layout.sectionInset = UIEdgeInsetsMake(0, margin, 0, margin);
        layout;
    });
    
    //创建UICollectionView
    
    UICollectionView *collectionView = ({
         UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
        collectionView.backgroundColor = [UIColor brownColor];
        collectionView.center = self.view.center;
        collectionView.bounds = CGRectMake(0, 0, self.view.bounds.size.width, 200);
        //设置滚动条隐藏
        collectionView.showsHorizontalScrollIndicator = NO;
        [self.view addSubview:collectionView];
        //设置数据源方法
        collectionView.dataSource = self;
        collectionView;
    });