When to use static variable and self keyword
    self.list = playList;

    - (id)init {
        if (self = [super init]) {
            [self createDemoData];
        }
        return self;
    }

    static NSString *CellIdentifier = @"CellIdentifier";

Hello, I still couldn't figure out when to use these two keywords, especially static.
When to use static variable and self keyword
===

    self.list = playList;

    - (id)init {
        if (self = [super init]) {
            [self createDemoData];
        }
        return self;
    }

    static NSString *CellIdentifier = @"CellIdentifier";

Hello, I still couldn't figure out when to use these two keywords, especially static.