iOS中链式编程中最经典的例子是Masonry为代表的代码形式，代码如下:

make.edges.equalTo(superview).with.insets(100);

Objective-C 链式编程

Objective-C中实现链式编程主要是通过Block来实现，利用方法的点式调用,自定义FEHeaderView，定义如下:

@class FEHeaderView;

typedef FEHeaderView *(^FEHeaderBlock)(UIColor *color);

typedef FEHeaderView *(^FEHeaderAssignBlock)(CGFloat num);

@interface FEHeaderView : UIView


- (FEHeaderBlock)bgColor;

- (FEHeaderAssignBlock)borderWidth;

- (FEHeaderBlock)borderColor;

@end

实现如下:

@implementation FEHeaderView


- (FEHeaderBlock)bgColor {
    FEHeaderBlock block = ^(UIColor *color) {
        self.backgroundColor = color;
        return self;
    };
    return block;
}

- (FEHeaderAssignBlock)borderWidth {
    FEHeaderAssignBlock block = ^(CGFloat width) {
        self.layer.masksToBounds = YES;
        self.layer.borderWidth = width;
        return self;
    };
    return block;
}

- (FEHeaderBlock)borderColor {
    FEHeaderBlock block = ^(UIColor *color) {
        self.layer.borderColor = color.CGColor;
        return self;
    };
    return block;
}

@end

测试代码:

   FEHeaderView *view = [[FEHeaderView alloc] initWithFrame:CGRectMake(100, 200, 100, 100)];
    
    view.bgColor([UIColor grayColor]).borderWidth(3.0).borderColor([UIColor redColor]);
    
    [self.view addSubview:view];

FlyElephant.png

Swift 链式编程

Swift中的实现链式编程比Objective-C中简单很多，通过func和extension即可实现.
扩展UIView:

extension UIView {
    
    func bgColor(color:UIColor) -> UIView {
        self.backgroundColor = color
        return self
    }
    
    func borderColor(color:UIColor) -> UIView {
        self.layer.borderColor = color.cgColor
        self.layer.masksToBounds = true
        return self
    }
    
    func borderWidth(width:Float) -> UIView {
        self.layer.borderWidth = CGFloat(width)
        return self
    }
    
}

测试代码:

let view:UIView = UIView(frame: CGRect(x: 100, y: 200, width: 100, height: 100)).bgColor(color: UIColor.red).borderColor(color: UIColor.gray).borderWidth(width: 5.0)
        self.view.addSubview(view)

FlyElephant.png