registerNib 和 loadNibNamed

// Beginning in iOS 6, clients can register a nib or class for each cell.
// If all reuse identifiers are registered, use the newer -dequeueReusableCellWithIdentifier:forIndexPath: to guarantee that a cell instance is returned.
// Instances returned from the new dequeue method will also be properly sized when they are returned.
- (void)registerNib:(nullable UINib *)nib forCellReuseIdentifier:(NSString *)identifier NS_AVAILABLE_IOS(5_0);

@interface NSBundle(UINibLoadingAdditions)
- (NSArray *)loadNibNamed:(NSString *)name owner:(id)owner options:(NSDictionary *)options;
@end