Objective-C notes

Objective-C notes.md

Obj-C/iOS dev notes

• Use NS_DESIGNATED_INITIALIZER for designated initializers in header (>= iOS 8)

  // foo.h
  - (id)initWithFoo:(NSString *)foo NS_DESIGNATED_INITIALIZER;  

• Use copy on NSString and `NSArray1 properties; (obviously) does not modify string at original pointer.

  @property (copy, nonatomic) NSString *foo;
  @property (copy, nonatomic) NSArray *bar;

• Register table view reuse identifiers inside data sources.

  // TableViewCell.h
  extern NSString * const TableViewCellReuseIdentifier;
  
  // TabieViewCell.m
  NSString * const TableViewCellReuseIdentifier = @"TableViewCellReuseIdentifier";
  
  // TableViewDataSource.h
  - (void)registerReuseableCellsWithTableView:(UITableView *)tableView;
  
  // TableViewDataSource.m
  - (void)registerReuseableCellsWithTableView:(UITableView *)tableView {
    [tableView registerClass:[TableViewCell class]
      forCellReuseIdentifier:TableViewCellReuseIdentifier];
  }
  
  // TableViewController.m
  [self.dataSource registerReuseableCellsWithTableView:self.tableView];

• Use instancetype as init type where possible (source).

• To set UINavigationBar back button image:

  [[UINavigationBar appearance] setBackIndicatorImage:[UIImage imageNamed:@"back.png"]];
  [[UINavigationBar appearance] setBackIndicatorTransitionMaskImage:[[UIImage alloc] init]];

• Use weak references to delegates in delegators; otherwise, the delegate will never de-allocate.

  @property (weak, nonatomic) id<FooDelegate> delegate;