Objective-C通过block实现链式编程
##1.NSObject+Then ###eg:
NSObject *foo = [[[NSObject alloc]init]then:^(id _Nonnull obj) {
// next...
}];
##2.UIXX+Chain
UIView *v = UIView.new.ht_frame(CGRectMake(0, 0, 100, 100))
.ht_backgroundColor([UIColor cyanColor])
.ht_addToSuperView(self.view);