Advanced Key-Value Observing

Author: Martin Kiss http://twitter.com/imartinkiss
Presented on BAiOS #1 https://www.facebook.com/bratislavaios

Transcript

1. void (^Blocks)(BOOL Advanced);
2. void (^Blocks)(BOOL Advanced); + Anonymné funkcie, resp. kus kódu uložený do premennej BOOL (^shouldContinue)(BOOL success); shouldContinue = ^BOOL (BOOL success) { return success; }; shouldContinue(YES); + Kopírujú do seba premenné + Dlhodobé uloženie kopírovaním + Väčšina callbackov od iOS 4.0
3. Bloky namiesto podtriedy GCD Block KVO Retain Cykly
4. Bloky namiesto podtriedy
5. Bloky namiesto podtriedy + Bloky v properties spúšťané metódami @property (nonatomic, copy) void (^updateBlock)(); - (void)update { if (self.updateBlock) self.updateBlock(); } + Kód v inej triede, napríklad v kontroléri + Kód v kontexte, kde sa používa + Menej tried
6. - (void)viewDidLoad { [super viewDidLoad]; self.cells = [[NSMutableArray alloc] init]; BAiOSCell *strongFirstCell = [[BAiOSCell alloc] initWithStyle:UITableViewCellStyleValue2 reuseIdentifier:nil]; __weak BAiOSCell *firstCell = strongFirstCell; firstCell.textLabel.text = @"Tap to update"; firstCell.updateBlock = ^{ // Set the content firstCell.detailTextLabel.text = [NSString stringWithFormat:@"%li", random()]; }; [firstCell update]; firstCell.selectionBlock = ^{ // Do something [firstCell update]; }; [self.cells addObject:firstCell]; }
7. - (void)viewDidLoad { [super viewDidLoad]; self.cells = [[NSMutableArray alloc] init]; BAiOSCell *strongFirstCell = [[BAiOSCell alloc] initWithStyle:UITableViewCellStyleValue2 reuseIdentifier:nil]; __weak BAiOSCell *firstCell = strongFirstCell; firstCell.textLabel.text = @"Tap to update"; firstCell.updateBlock = ^{ // Set the content firstCell.detailTextLabel.text = [NSString stringWithFormat:@"%li", random()]; }; [firstCell update]; firstCell.selectionBlock = ^{ // Do something [firstCell update]; }; [self.cells addObject:firstCell]; }
8. - (void)viewDidLoad { [super viewDidLoad]; self.cells = [[NSMutableArray alloc] init]; BAiOSCell *strongFirstCell = [[BAiOSCell alloc] initWithStyle:UITableViewCellStyleValue2 reuseIdentifier:nil]; __weak BAiOSCell *firstCell = strongFirstCell; firstCell.textLabel.text = @"Tap to update"; firstCell.updateBlock = ^{ // Set the content firstCell.detailTextLabel.text = [NSString stringWithFormat:@"%li", random()]; }; [firstCell update]; firstCell.selectionBlock = ^{ // Do something [firstCell update]; }; [self.cells addObject:firstCell]; }
9. - (void)viewDidLoad { [super viewDidLoad]; self.cells = [[NSMutableArray alloc] init]; BAiOSCell *strongFirstCell = [[BAiOSCell alloc] initWithStyle:UITableViewCellStyleValue2 reuseIdentifier:nil]; __weak BAiOSCell *firstCell = strongFirstCell; firstCell.textLabel.text = @"Tap to update"; firstCell.updateBlock = ^{ // Set the content firstCell.detailTextLabel.text = [NSString stringWithFormat:@"%li", random()]; }; [firstCell update]; firstCell.selectionBlock = ^{ // Do something [firstCell update]; }; [self.cells addObject:firstCell]; }
10. - (void)viewDidLoad { [super viewDidLoad]; self.cells = [[NSMutableArray alloc] init]; BAiOSCell *strongFirstCell = [[BAiOSCell alloc] initWithStyle:UITableViewCellStyleValue2 reuseIdentifier:nil]; __weak BAiOSCell *firstCell = strongFirstCell; firstCell.textLabel.text = @"Tap to update"; firstCell.updateBlock = ^{ // Set the content firstCell.detailTextLabel.text = [NSString stringWithFormat:@"%li", random()]; }; [firstCell update]; firstCell.selectionBlock = ^{ // Do something [firstCell update]; }; [self.cells addObject:firstCell]; }
11. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return self.cells.count; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { return [self.cells objectAtIndex:indexPath.row]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { [tableView deselectRowAtIndexPath:indexPath animated:YES]; // Cell knows what to do [[self.cells objectAtIndex:indexPath.row] didSelect]; }
12. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return self.cells.count; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { return [self.cells objectAtIndex:indexPath.row]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { [tableView deselectRowAtIndexPath:indexPath animated:YES]; // Cell knows what to do [[self.cells objectAtIndex:indexPath.row] didSelect]; }
13. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return self.cells.count; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { return [self.cells objectAtIndex:indexPath.row]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { [tableView deselectRowAtIndexPath:indexPath animated:YES]; // Cell knows what to do [[self.cells objectAtIndex:indexPath.row] didSelect]; }
14. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return self.cells.count; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { return [self.cells objectAtIndex:indexPath.row]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { [tableView deselectRowAtIndexPath:indexPath animated:YES]; // Cell knows what to do [[self.cells objectAtIndex:indexPath.row] didSelect]; }
15. GCD
16. Grand Central Dispatch + Nízkoúrovňová C knižnica + Nahradzuje thready za queues + Vytvorené pre viacjadrové počítače + Pracuje s blokmi dispatch_async dispatch_sync dispatch_after dispatch_apply dispatch_once
17. Background Queue Touch Main Queue Task Touch Update UI Task Touch Touch
18. dispatch_queue_t backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_async(backgroundQueue, ^{ // Do heavy task in background NSString *content = [self parse]; dispatch_async(dispatch_get_main_queue(), ^{ // Update UI on main queue/thread self.contentLabel.text = content; }); });
19. dispatch_queue_t backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_async(backgroundQueue, ^{ // Do heavy task in background NSString *content = [self parse]; dispatch_async(dispatch_get_main_queue(), ^{ // Update UI on main queue/thread self.contentLabel.text = content; }); });
20. dispatch_queue_t backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_async(backgroundQueue, ^{ // Do heavy task in background NSString *content = [self parse]; dispatch_async(dispatch_get_main_queue(), ^{ // Update UI on main queue/thread self.contentLabel.text = content; }); });
21. dispatch_queue_t backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0); dispatch_async(backgroundQueue, ^{ // Do heavy task in background NSString *content = [self parse]; dispatch_async(dispatch_get_main_queue(), ^{ // Update UI on main queue/thread self.contentLabel.text = content; }); });
22. dispatch_time_t delay = dispatch_time(DISPATCH_TIME_NOW, seconds * NSEC_PER_SEC); dispatch_after(delay, dispatch_get_main_queue(), ^{ // Delayed execution });
23. @interface NSObject (GCD) - (void)performOnMainThread:(void(^)(void))block wait:(BOOL)wait; - (void)performAsynchronous:(void(^)(void))block; - (void)performAfter:(NSTimeInterval)seconds block:(void(^)(void))block; @end [self performAfter:0.25 block:^{ // Something }]; [self performAsynchronous:^{ // Something }];
24. Block KVO
25. [self observe:@"video.title" withBlock: ^(NSString *oldVideoTitle, NSString *newVideoTitle) { // Update UI weakSelf.titleLabel.text = newVideoTitle; }]; Available on GitHub
26. Retain Cykly
27. firstCell.selectionBlock = ^{ [ }; UIViewController self NSArray cells UITableViewCell firstCell void (^)(void) selectionBlock strong strong copy __strong self doSomething];
28. firstCell.selectionBlock = ^{ [ }; doSomething]; __weak id weakSelf = self; weakSelf __weak UIViewController self NSArray cells UITableViewCell firstCell void (^)(void) selectionBlock strong strong copy