Remove one delegate method. Add dequeueReusableCellWithIdentifier met…

…hod. Now it works like UITableView. We can have different types of cells now.

StreamView/EKStreamView.h

@@ -8,6 +8,12 @@
 
 #import <UIKit/UIKit.h>
 
+@protocol EKResusableCell <NSObject>
+
+@property (nonatomic, retain) NSString *reuseIdentifier;
+
+@end
+
 
 
 @interface EKStreamViewCellInfo : NSObject 
@@ -16,7 +22,7 @@
 @property (nonatomic, assign) NSUInteger index;
 
 // You SHOULD ONLY access this property when this object is in visibleCellInfo!
-@property (nonatomic, assign) UIView *cell;
+@property (nonatomic, assign) UIView<EKResusableCell> *cell;
 
 @end
 
@@ -29,9 +35,8 @@
 
 - (NSInteger)numberOfCellsInStreamView:(EKStreamView *)streamView;
 - (NSInteger)numberOfColumnsInStreamView:(EKStreamView *)streamView;
-- (UIView *)cellForStreamView:(EKStreamView *)streamView;
+- (UIView<EKResusableCell> *)cellForStreamView:(EKStreamView *)streamView atIndex:(NSInteger)index;
 - (CGFloat)streamView:(EKStreamView *)streamView heightForCellAtIndex:(NSInteger)index;
-- (void)streamView:(EKStreamView *)streamView setContentForCell:(UIView *)cell atIndex:(NSInteger)index;
 
 @optional
 
@@ -50,14 +55,15 @@
     *cellHeightsByIndex,    // 1d
     *cellHeightsByColumn,   // 2d
     *heightsForColumns,     // 1d
-    *rectsForCells,         // 2d EKWaterfallCellInfo
-    *cellPool;              // 1d UIView
+    *rectsForCells;         // 2d EKWaterfallCellInfo
 
+    NSMutableDictionary *cellCache; // reuseIdentifier => NSMutableArray
     NSSet *visibleCellInfo;
 }
 
 @property (nonatomic, assign) id<EKStreamViewDelegate> delegate;
 
+- (id<EKResusableCell>)dequeueReusableCellWithIdentifier:(NSString *)identifier;
 - (void)reloadData;
 
 @end

StreamView/EKStreamView.m

@@ -37,11 +37,10 @@ @interface EKStreamView()
 
 - (void)setup;
 - (NSSet *)getVisibleCellInfo;
-- (UIView *)getCell;
 - (void)layoutCellWithCellInfo:(EKStreamViewCellInfo *)info;
 
 @property (nonatomic, retain) NSSet *visibleCellInfo;
-@property (nonatomic, retain) NSMutableArray *cellPool;
+@property (nonatomic, retain) NSMutableDictionary *cellCache;
 
 @end
 
@@ -60,7 +59,7 @@ - (void)layoutCellWithCellInfo:(EKStreamViewCellInfo *)info;
 
 @implementation EKStreamView
 
-@synthesize delegate, visibleCellInfo, cellPool;
+@synthesize delegate, visibleCellInfo, cellCache;
 
 - (id)initWithFrame:(CGRect)frame
 {
@@ -88,7 +87,7 @@ - (void)dealloc
     [heightsForColumns release];
     [rectsForCells release];
     [visibleCellInfo release];
-    [cellPool release];
+    [cellCache release];
     [super dealloc];
 }
 
@@ -98,7 +97,7 @@ - (void)reloadData
     [cellHeightsByColumn removeAllObjects];
     [heightsForColumns removeAllObjects];
     [rectsForCells removeAllObjects];
-    [cellPool removeAllObjects];
+    [cellCache removeAllObjects];
 
     // calculate height for all cells
     NSInteger numberOfColumns = [delegate numberOfColumnsInStreamView:self];
@@ -170,6 +169,18 @@ - (void)reloadData
     free(cellX);
 }
 
+- (id<EKResusableCell>)dequeueReusableCellWithIdentifier:(NSString *)identifier
+{
+    NSMutableArray *cellArray = [cellCache objectForKey:identifier];
+    id<EKResusableCell> cell = nil;
+    if ([cellArray count] > 0) {
+        cell = [[[cellArray lastObject] retain] autorelease];
+        [cellArray removeLastObject];
+    } 
+
+    return cell;
+}
+
 #pragma mark - Private Methods
 
 - (NSSet *)getVisibleCellInfo
@@ -199,24 +210,10 @@ - (NSSet *)getVisibleCellInfo
     return ret;
 }
 
-- (UIView *)getCell
-{
-    UIView *cell;
-    if ([cellPool count] > 0) {
-        cell = [[[cellPool lastObject] retain] autorelease];
-        [cellPool removeLastObject];
-    } else {
-        cell = [delegate cellForStreamView:self];
-    }
-
-    return cell;
-}
-
 - (void)layoutCellWithCellInfo:(EKStreamViewCellInfo *)info
 {
-    UIView *cell = [self getCell];
+    UIView<EKResusableCell> *cell = [delegate cellForStreamView:self atIndex:info.index];
     cell.frame = info.frame;
-    [delegate streamView:self setContentForCell:cell atIndex:info.index];
     info.cell = cell;
     [self addSubview:cell];
 }
@@ -231,7 +228,7 @@ - (void)setup
     cellHeightsByColumn = [[NSMutableArray alloc] initWithCapacity:5];
     heightsForColumns = [[NSMutableArray alloc] initWithCapacity:5];
     rectsForCells = [[NSMutableArray alloc] initWithCapacity:5];
-    cellPool = [[NSMutableArray alloc] initWithCapacity:20];
+    cellCache = [[NSMutableDictionary alloc] initWithCapacity:5];
 }
 
 @end
@@ -240,13 +237,6 @@ - (void)setup
 
 
 
-// TODO: in scrollView did scroll to position delegate method,
-// 1. determine which cells should be visible
-// 2. compare should-be-visible list to the current visibleCells list
-//    For any missing cells, deque and setup it to the position;
-//    for any cells that is there but not in should-be-visible list, remove it and put it into the queue.
-
-
 @implementation EKStreamViewUIScrollViewDelegate
 
 @synthesize streamView;
@@ -255,11 +245,20 @@ - (void)scrollViewDidScroll:(UIScrollView *)scrollView
 {
     NSSet *newVisibleCellInfo = [streamView getVisibleCellInfo];
     NSSet *visibleCellInfo = streamView.visibleCellInfo;
-    NSMutableArray *cellPool = streamView.cellPool;
+    NSMutableDictionary *cellCache = streamView.cellCache;
+
+
     for (EKStreamViewCellInfo *info in visibleCellInfo) {
         if (![newVisibleCellInfo containsObject:info]) {
             // info.cell.retainCount: 1
-            [cellPool addObject:info.cell];
+            NSString *cellID = info.cell.reuseIdentifier;
+            NSMutableArray *cellArray = [cellCache objectForKey:cellID];
+            if (cellArray == nil) {
+                cellArray = [NSMutableArray arrayWithCapacity:10];
+                [cellCache setObject:cellArray forKey:cellID];
+            }
+
+            [cellArray addObject:info.cell];
             // info.cell.retainCount: 2
             [info.cell removeFromSuperview];
             // info.cell.retainCount: 1

StreamView/EKViewController.m

@@ -66,9 +66,27 @@ - (NSInteger)numberOfColumnsInStreamView:(EKStreamView *)streamView
     return 3;
 }
 
-- (UIView *)cellForStreamView:(EKStreamView *)streamView
+- (UIView *)cellForStreamView:(EKStreamView *)streamView atIndex:(NSInteger)index
 {
-    return [[[MyCell alloc] initWithFrame:CGRectMake(0, 0, 100, 100)] autorelease];
+    static NSString *CellID1 = @"MyCell1";
+    static NSString *CellID2 = @"MyCell2";
+
+    BOOL redCell = index % 3 == 0;
+    NSString *CellID =  CellID1;
+
+    MyCell *cell;
+
+    cell = (MyCell *)[streamView dequeueReusableCellWithIdentifier:CellID];
+
+    if (cell == nil) {
+        cell = [[[MyCell alloc] initWithFrame:CGRectMake(0, 0, 100, 100)] autorelease];
+        cell.reuseIdentifier = CellID;
+//        if (redCell) cell.label.textColor = [UIColor redColor];
+    }
+
+    cell.label.text = [NSString stringWithFormat:@"%d",index];
+
+    return cell;
 }
 
 - (CGFloat)streamView:(EKStreamView *)streamView heightForCellAtIndex:(NSInteger)index

StreamView/MyCell.h

@@ -7,8 +7,12 @@
 //
 
 #import <UIKit/UIKit.h>
+#import "EKStreamView.h"
 
-@interface MyCell : UIView
+@interface MyCell : UIView<EKResusableCell>
+{
+    NSString *reuseIdentifier;
+}
 
 @property (nonatomic, readonly) UILabel *label;
 

StreamView/MyCell.m

@@ -11,12 +11,13 @@
 
 @implementation MyCell
 
-@synthesize label;
+@synthesize label, reuseIdentifier;
 
 
 - (void)dealloc
 {
     [label release];
+    [reuseIdentifier release];
     [super dealloc];
 }