第四十一篇、Masonry利用Block实现链式编程

一直都觉得使用Masonry的时候语法特别优雅,很早的时候就想尝试下怎么实现,

一直都没弄明白,直到最近看见一篇叫block实现链式编程的

1.方法的返回类型是代码块

　　>代码块的返回类型是该类的实例变量

　　>在返回的代码块中，设置完相关的操作，并把实例对象返回

使用实例：

 UIButton * btn = [UIButton button].normalTitle(@"普通状态").normalImage([UIImage imageNamed:@"icon_help"]).selectedTitle(@"选中状态");

给系统的UIkit框架中的UIButton拓展分类

/// 声明文件
@interface UIButton (JQExtension)
/// 连接符,没啥实际意义,蛋疼的时候可以无限.set....
- (instancetype)set;

+ (instancetype)button;
/// 设置普通状态标题
- (UIButton *(^)(NSString *))normalTitle;

/// 设置选中状态标题
- (UIButton *(^)(NSString *))selectedTitle;

/// 设置高亮状态标题
- (UIButton *(^)(NSString *))highlightTitle;

/// 设置普通状态图片
- (UIButton *(^)(UIImage *))normalImage;

/// 设置选中状态图片
- (UIButton *(^)(UIImage *))selectedImage;

/// 设置高亮状态图片
- (UIButton *(^)(UIImage *))highlightedImage;

/// 设置普通状态背景图片
- (UIButton *(^)(UIImage *))normalBackgroundImage;

/// 设置高亮状态背景图片
- (UIButton *(^)(UIImage *))highlightedBackgroundImage;

/// 设置选中状态背景图片
- (UIButton *(^)(UIImage *))selectedBackgroundImage;

@end

实现文件
#import "UIButton+GKExtension.h"

@implementation UIButton (GKExtension)
- (instancetype)set {
    return self;
}

+ (instancetype)button {
    return [self buttonWithType:UIButtonTypeCustom];
}

- (UIButton *(^)(NSString *))normalTitle {
    return ^(NSString *title){
        [self setTitle:title forState:UIControlStateNormal];
        return self;
    };
}

- (UIButton *(^)(NSString *))selectedTitle {
    return ^(NSString *title){
        [self setTitle:title forState:UIControlStateNormal];
        return self;
    };
}

- (UIButton *(^)(NSString *))highlightTitle {
    return ^(NSString *title){
        [self setTitle:title forState:UIControlStateNormal];
        return self;
    };
}

- (UIButton *(^)(UIImage *))normalImage {
    return ^(UIImage *image){
        [self setImage:image forState:UIControlStateNormal];
        return self;
    };
}
- (UIButton *(^)(UIImage *))normalBackgroundImage {
    return ^(UIImage *image){
        [self setBackgroundImage:image forState:UIControlStateNormal];
        return self;
    };
}
- (UIButton *(^)(UIImage *))selectedImage {
    return ^(UIImage *image){
        [self setImage:image forState:UIControlStateSelected];
        return self;
    };
}

- (UIButton *(^)(UIImage *))selectedBackgroundImage {
    return ^(UIImage *image){
        [self setBackgroundImage:image forState:UIControlStateSelected];
        return self;
    };
}

- (UIButton *(^)(UIImage *))highlightedImage {
    return ^(UIImage *image){
        [self setImage:image forState:UIControlStateHighlighted];
        return self;
    };
}

- (UIButton *(^)(UIImage *))highlightedBackgroundImage {
    return ^(UIImage *image){
        [self setBackgroundImage:image forState:UIControlStateHighlighted];
        return self;
    };
}