Kaedah mencipta paparan adalah sangat pelik dan saya tidak faham maksudnya. Tolong beri saya nasihat

Kodnya adalah seperti berikut:

 UIView *cancel = ({
                    

                    UIButton *view= [UIButton new];
                    view.contentHorizontalAlignment=UIControlContentHorizontalAlignmentLeft;
                    [view setTitle:NSLocalizedString(@"cancel", nil) forState:UIControlStateNormal];
                    [view setTitleColor:Global_trelloBlue forState:UIControlStateNormal];
                    view.titleLabel.font = [UIFont systemFontOfSize:15];
                    [createListView addSubview:view];
                    view.tag = 999;
                    [view makeConstraints:^(MASConstraintMaker *make) {
                        make.left.equalTo(20);
                        make.bottom.equalTo(-1);
                        make.width.equalTo(100);
                    }];
                    [view sizeToFit];
                    view.alpha = 0;
                    [self layoutIfNeeded];
                    //cancel点击事件
                    @weakify(self, view, textView, createListView, listView, add, addCard)
                    [[view rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(id x) {
                        @strongify(self, view, textView, createListView, listView, add, addCard)
                        //footer高度还原
                        [createListView updateConstraints:^(MASConstraintMaker *make) {
                            make.height.equalTo(44);
                        }];
                        //list减去footer增加的高度(在这里做是为了动效)
                        [listView updateConstraints:^(MASConstraintMaker *make) {
                            make.height.equalTo(listView.yyHeight-44);
                        }];
                     
                        //隐藏textView
                        textView.alpha = 0;
                        
                        [UIView animateWithDuration:0.25 animations:^{
                            //cancel隐藏
                            view.alpha = 0;
                            //add隐藏
                            add.alpha = 0;
                            //addCard显示
                            addCard.alpha = 1;
                            [self.viewController.navigationController setNavigationBarHidden:NO animated:YES];
                            [self layoutIfNeeded];
                        }];
                        [textView resignFirstResponder];
                    }];
                    view;
                });