Support for data sources with heterogeneous cell reuse identifiers

TGRDataSource/TGRArrayDataSource.h

@@ -36,7 +36,7 @@
  Initializes the data source.
 
  @param items The items managed by the data source.
- @param reuseIdentifier The cell reuse identifier.
+ @param reuseIdentifier The default cell reuse identifier.
  @param configureCellBlock A block that will be called when the view asks for a cell in a particular location.
 
  @return An initialized data source.
@@ -45,5 +45,19 @@
 cellReuseIdentifier:(NSString *)reuseIdentifier
  configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock;
 
+/**
+ Initializes the data source with a custom cell reuse identifier block.
+
+ @param items The items managed by the data source.
+ @param reuseIdentifierBlock A block that will be called when the view asks for
+ the reuse identifier of cell in a particular location.
+ @param configureCellBlock A block that will be called when the view asks for a 
+ cell in a particular location.
+
+ @return An initialized data source.
+ */
+-  (id)initWithItems:(NSArray *)items
+reuseIdentifierBlock:(TGRDataSourceReuseIdentifierBlock)reuseIdentifierBlock
+  configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock;
 
 @end

TGRDataSource/TGRArrayDataSource.m

@@ -28,7 +28,22 @@ - (id)initWithItems:(NSArray *)items
 cellReuseIdentifier:(NSString *)reuseIdentifier
  configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock
 {
-    self = [super initWithCellReuseIdentifier:reuseIdentifier configureCellBlock:configureCellBlock];
+    self = [super initWithCellReuseIdentifier:reuseIdentifier
+                           configureCellBlock:configureCellBlock];
+
+    if (self) {
+        _items = [items copy];
+    }
+
+    return self;
+}
+
+-  (id)initWithItems:(NSArray *)items
+reuseIdentifierBlock:(TGRDataSourceReuseIdentifierBlock)reuseIdentifierBlock
+  configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock
+{
+    self = [super initWithReuseIdentifierBlock:reuseIdentifierBlock
+                            configureCellBlock:configureCellBlock];
 
     if (self) {
         _items = [items copy];

TGRDataSource/TGRDataSource.h

@@ -22,6 +22,7 @@
 
 #import <UIKit/UIKit.h>
 
+typedef NSString *(^TGRDataSourceReuseIdentifierBlock)(NSIndexPath *indexPath, id item);
 typedef void (^TGRDataSourceCellBlock)(id cell, id item);
 
 /**
@@ -31,26 +32,49 @@ typedef void (^TGRDataSourceCellBlock)(id cell, id item);
 @interface TGRDataSource : NSObject <UITableViewDataSource, UICollectionViewDataSource>
 
 /**
- The cell reuse identifier.
+ A block that will be called when the view asks for the reuse identifier of cell in a 
+ particular location.
  */
-@property (copy, nonatomic, readonly) NSString *cellReuseIdentifier;
+@property (copy, nonatomic, readonly) TGRDataSourceReuseIdentifierBlock reuseIdentifierBlock;
 
 /**
  A block that will be called when the view asks for a cell in a particular location.
  */
 @property (copy, nonatomic, readonly) TGRDataSourceCellBlock configureCellBlock;
 
 /**
- Initializes the data source.
+ Initializes the data source using a single reuse identifier. 
 
- @param reuseIdentifier The cell reuse identifier.
- @param configureCellBlock A block that will be called when the view asks for a cell in a particular location.
+ @discussion This initializer internally creates a custom reuse identifier block 
+ that will return the default reuse identifier for all cells. This is useful
+ when a data source provide a single kind of cell, for homogeneous views.
+
+ @param defaultReuseIdentifier The default cell reuse identifier.
+ @param configureCellBlock A block that will be called when the view asks for a 
+ cell in a particular location.
 
  @return An initialized data source.
  */
-- (id)initWithCellReuseIdentifier:(NSString *)reuseIdentifier
+- (id)initWithCellReuseIdentifier:(NSString *)defaultReuseIdentifier
                configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock;
 
+/**
+ Initializes the data source with a custom cell reuse identifier block.
+
+ @discussion This is the designated initializer of this class. It creates
+ a data source that provides multiple kinds of cell that can be used in
+ the implementation of heterogeneous views.
+
+ @param reuseIdentifierBlock A block that will be called when the view asks for
+ the reuse identifier of cell in a particular location.
+ @param configureCellBlock A block that will be called when the view asks for a
+ cell in a particular location.
+
+ @return An initialized data source.
+ */
+- (id)initWithReuseIdentifierBlock:(TGRDataSourceReuseIdentifierBlock)reuseIdentifierBlock
+                configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock;
+
 /**
  Returns a data source item in a particular location.
  */

TGRDataSource/TGRDataSource.m

@@ -25,21 +25,32 @@
 
 @interface TGRDataSource ()
 
-@property (copy, nonatomic) NSString *cellReuseIdentifier;
+@property (copy, nonatomic) TGRDataSourceReuseIdentifierBlock reuseIdentifierBlock;
 @property (copy, nonatomic) TGRDataSourceCellBlock configureCellBlock;
 
 @end
 
 @implementation TGRDataSource
 
-- (id)initWithCellReuseIdentifier:(NSString *)reuseIdentifier
-               configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock
-{
-    self = [super init];
+- (id)initWithCellReuseIdentifier:(NSString *)defaultReuseIdentifier
+               configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock {
+
+    TGRDataSourceReuseIdentifierBlock defaultBlock = ^NSString *(NSIndexPath *indexPath, id item) {
+        return defaultReuseIdentifier;
+    };
+
+    self = [self initWithReuseIdentifierBlock:defaultBlock
+                           configureCellBlock:configureCellBlock];
+
+    return self;
+}
+
+- (id)initWithReuseIdentifierBlock:(TGRDataSourceReuseIdentifierBlock)reuseIdentifierBlock
+                configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock {
 
+    self = [super init];
     if (self) {
-        self.cellReuseIdentifier = reuseIdentifier;
-        self.configureCellBlock = configureCellBlock;
+        self.reuseIdentifierBlock = reuseIdentifierBlock;
     }
 
     return self;
@@ -62,11 +73,19 @@ - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger
     return 0;
 }
 
-- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
-    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:self.cellReuseIdentifier
-                                                            forIndexPath:indexPath];
+- (UITableViewCell *)tableView:(UITableView *)tableView
+         cellForRowAtIndexPath:(NSIndexPath *)indexPath
+{
     id item = [self itemAtIndexPath:indexPath];
 
+    NSString *reuseIdentifier = @"";
+    if (self.reuseIdentifierBlock) {
+        reuseIdentifier = self.reuseIdentifierBlock(indexPath, item);
+    }
+
+    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reuseIdentifier
+                                                            forIndexPath:indexPath];
+
     if (self.configureCellBlock) {
         self.configureCellBlock(cell, item);
     }
@@ -86,10 +105,16 @@ - (NSInteger)collectionView:(UICollectionView *)collectionView
 - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                   cellForItemAtIndexPath:(NSIndexPath *)indexPath
 {
-    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:self.cellReuseIdentifier
-                                                                           forIndexPath:indexPath];
     id item = [self itemAtIndexPath:indexPath];
 
+    NSString *reuseIdentifier = @"";
+    if (self.reuseIdentifierBlock) {
+        reuseIdentifier = self.reuseIdentifierBlock(indexPath, item);
+    }
+
+    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier
+                                                                           forIndexPath:indexPath];
+
     if (self.configureCellBlock) {
         self.configureCellBlock(cell, item);
     }

TGRDataSource/TGRFetchedResultsDataSource.h

@@ -39,12 +39,28 @@
 
  @param controller The `NSFetchedResultsController` object managed by this data source.
  @param reuseIdentifier The cell reuse identifier.
- @param configureCellBlock A block that will be called when the view asks for a cell in a particular location.
+ @param configureCellBlock A block that will be called when the view asks for a cell in 
+ a particular location.
 
  @return An initialized data source.
  */
 - (id)initWithFetchedResultsController:(NSFetchedResultsController *)controller
                    cellReuseIdentifier:(NSString *)reuseIdentifier
                     configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock;
 
+/**
+ Initializes the data source without a default cell reuse identifier.
+
+ @param controller The `NSFetchedResultsController` object managed by this data source.
+ @param reuseIdentifierBlock A block that will be called when the view asks for
+ the reuse identifier of cell in a particular location.
+ @param configureCellBlock A block that will be called when the view asks for a cell in 
+ a particular location.
+
+ @return An initialized data source.
+ */
+- (id)initWithFetchedResultsController:(NSFetchedResultsController *)controller
+                  reuseIdentifierBlock:(TGRDataSourceReuseIdentifierBlock)reuseIdentifierBlock
+                    configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock;
+
 @end

TGRDataSource/TGRFetchedResultsDataSource.m

@@ -37,6 +37,20 @@ - (id)initWithFetchedResultsController:(NSFetchedResultsController *)controller
     return self;
 }
 
+- (id)initWithFetchedResultsController:(NSFetchedResultsController *)controller
+                  reuseIdentifierBlock:(TGRDataSourceReuseIdentifierBlock)reuseIdentifierBlock
+                    configureCellBlock:(TGRDataSourceCellBlock)configureCellBlock
+{
+    self = [super initWithReuseIdentifierBlock:reuseIdentifierBlock
+                            configureCellBlock:configureCellBlock];
+
+    if (self) {
+        _fetchedResultsController = controller;
+    }
+
+    return self;
+}
+
 - (id)itemAtIndexPath:(NSIndexPath *)indexPath {
     return [self.fetchedResultsController objectAtIndexPath:indexPath];
 }