如何在 iPhone 的滚动视图中动态加载视图中的图像

Question

我想在滚动视图中显示许多图像，例如缩略图，并且我希望动态显示图像，我们像表格视图单元格一样向下或向左滚动

你能告诉我怎么做吗...

谢谢

使用以下代码..当我们滚动滚动视图时，我会调用此代码并能够动态显示图像（仅可见），但问题是..当使用滚动条滚动时，我会得到两个图像..垂直和水平..只有当我滚动时才会发生..任何人都可以帮助我吗..？

int tileSize;
    int imgSize;
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){
        tileSize = 255;
        imgSize = 247;
    }else{
        tileSize = 120;
        imgSize = 116;
    }
    CGRect visibleBounds = [songsContainer bounds];
    for (UIView *tile in [songsContainer subviews]) {
        CGRect scaledTileFrame =[tile frame];
        if (! CGRectIntersectsRect(scaledTileFrame, visibleBounds)) {
            for(UIView *view in [tile subviews])
                [view removeFromSuperview];
            [recycledCells addObject:tile];
            [tile removeFromSuperview];
        }
    }
    int maxRow =[songsDict count]-1; // this is the maximum possible row
    int maxCol = noOfRowsInCell-1;  // and the maximum possible column
    int firstNeededRow = MAX(0, floorf(visibleBounds.origin.y / tileSize));
    int firstNeededCol = MAX(0, floorf(visibleBounds.origin.x / tileSize));
    int lastNeededRow  = MIN(maxRow, floorf(CGRectGetMaxY(visibleBounds) / tileSize));
    int lastNeededCol  = MIN(maxCol, floorf(CGRectGetMaxX(visibleBounds) / tileSize));
    NSLog(@".........MaxRow-%d,MaxCol-%d,firstNeddedRow-%d,firstNeededcol-%d,lNR-%d,lNC%d",maxRow, maxCol, firstNeededRow,firstNeededCol,lastNeededRow,lastNeededCol);
    // iterate through needed rows and columns, adding any tiles that are missing
    for (int row = firstNeededRow; row <= lastNeededRow; row++) {
        NSMutableArray *tempArray = (NSMutableArray *)[songsDict objectAtIndex:row];
        for (int col = firstNeededCol; col <= lastNeededCol ; col++) {
            BOOL tileIsMissing = (firstVisibleRow > row || firstVisibleColumn > col || 
                                  lastVisibleRow  < row || lastVisibleColumn  < col);
            if (tileIsMissing) {
                UIView *tile = (UIView *)[self dequeueReusableTile];

                if (!tile) {
                    // the scroll view will handle setting the tile's frame, so we don't have to worry about it
                    tile = [[[UIView alloc] initWithFrame:CGRectZero] autorelease]; 
                    tile.backgroundColor = [UIColor clearColor];
                }
                //tile.image = image for row and col;
                // set the tile's frame so we insert it at the correct position
                CGRect frame = CGRectMake(tileSize * col, tileSize * row, imgSize, imgSize);
                tile.frame = frame;
                if(col<[tempArray count])
                    [self addContentForTile:tile:row:col];
                else tile.backgroundColor = [UIColor clearColor];
                [songsContainer addSubview:tile];

            }
        }
    }
    firstVisibleRow = firstNeededRow+1; firstVisibleColumn = firstNeededCol+1;
    lastVisibleRow  = lastNeededRow;  lastVisibleColumn  = lastNeededCol;

Answer 1

您要做的就是随心所欲地创建滚动视图。您必须决定是否需要网格布局或线性布局。此外，如果是网格，您是否希望它锁定到水平边界，锁定到垂直，所以它可以分别垂直或水平滚动。

一旦你把它整理好，那么我建议采用类似于 tableview 功能的架构。也就是说，创建单独的“单元格”来保存您的缩略图。一旦有了这些单元格，就可以将它们添加为滚动视图的子视图，在某些偏移处（您需要在 x/y 平面上进行一些数学运算）。

Answer 2

从滚动视图开始，将 UIImageView 中的每个图像作为子视图添加到特定位置的滚动视图。

要记住的一件事是仅将当前显示的图像及其直接邻居保存在内存中。