Example of if-less coding

If-less.m

- (void)switchPanel:(UIView*)currentPanel toPanel:(UIView*)newPanel;
{
    if (currentPanel == newPanel) return;
    
    /// This part of code describes all transitions between panels.
    /// empty mean that panel is null;
    /// non-empty : vice versa.
    
    NSString *empty = @"empty", *non_empty = @"non-empty";
    NSDictionary* switches = @{
      empty : @{
              non_empty : ^{
                  [self.panelContainer addSubview:newPanel];
              }},
      non_empty : @{
              empty : ^{
                  [currentPanel removeFromSuperview];
              },
              non_empty : ^{
                  newPanel.alpha = 0;
                  [self.panelContainer addSubview:newPanel];
                  [UIView animateWithDuration:0.5
                                   animations:^{
                                       newPanel.alpha = 1;
                                       currentPanel.alpha = 0;
                                   } completion:^(BOOL finished) {
                                       [currentPanel removeFromSuperview];
                                   }];

              }}
      };
    
    void(^block)() = ({
        NSString* currentPanelStatus = (currentPanel == nil) ? empty : non_empty;
        NSString* newPanelStatus = (newPanel == nil) ? empty : non_empty;
        
        switches[currentPanelStatus][newPanelStatus];
    });
    
    NSAssert(block != NULL, @"Uncovered condition detected");
    
    block();
}

- (void)reloadView
{
    NSAssert(self.panelContainer.subviews.count < 2, @"Inconsistent container content");
    UIView* currentPanel = self.panelContainer.subviews[0];
    UIView* newPanel = @{
                         @(PTLoginViewModelCredentialsState): self.credentialsPanel,
                         @(PTLoginViewModelLoadingState) : self.loadingPanel
                         }[@(self.model.state)];
    
    [self switchPanel:currentPanel toPanel:newPanel];
    
    [self.loginTextField setText:self.model.login];
    [self.passTextField setText:self.model.password];
}