piterwilson/precalculatedheightcolumnbaseduicollectionviewlayout

PrecalculatedHeightColumnBasedUICollectionViewLayout is a UICollectionViewLayout subclass where the items are placed in vertical columns that are laid out side by side. Each column has an arbitrary amount of items each with arbitrary heights. Each column is laid out independently from each other. (Looks like UITableView’s synced up to each other)

#PrecalculatedHeightColumnBasedUICollectionViewLayout

PrecalculatedHeightColumnBasedUICollectionViewLayout is a UICollectionViewLayout subclass where the items are placed in vertical columns that are layed out side by side. Each column has items of arbitrary heights.

The height of the items is provided by the items themselves (implementing the PrecalculatedHeightObject protocol). The protocol contains a sinle property that must be implemented:

-(float)precalculatedHeight;

The width of the columns is specified by the layout. (columnWidth property) as is the internal spacing between columns (columSpacing, rowSpacing properties)

Example :

The pseudo data structure

[
  [
      {precalculatedHeght : 1}
  ],
  [
      {precalculatedHeght : 1},
      {precalculatedHeght : 2},
      {precalculatedHeght : 3}
  ],
  [
      {precalculatedHeght : 1},
      {precalculatedHeght : 2},
      {precalculatedHeght : 2}
  ]
]

Results in:

┌─────┬─────┬─────┐
|  1  |  1  |  1  |
└─────┼─────┼─────┤
     |  2  |  2  |
     |     |     |
     ├─────┼─────┤
     |  3  |  2  |
     |     |     |
     |     ├─────┘
     └─────┘

#Installation

Download the sample project and copy the files under the PrecalculatedHeightColumnBasedUICollectionViewLayout folder

#Usage

##PrecalculatedHeightColumnBasedUICollectionViewLayoutDataSource

PrecalculatedHeightColumnBasedUICollectionViewLayout needs an object to act as its dataSource. The class may be of any type as long as it implements the PrecalculatedHeightColumnBasedUICollectionViewLayoutDataSource protocol.

-(id <PrecalculatedHeightObject>)objectForColumn:(int)column position:(int)position;

This call should return the Object that is positioned at the specified column and position (row) inside that column. The Object should implement the PrecalculatedHeightObject protocol.

-(int)numberObjectsInColumn:(int)column;

This call should return the number of Objects in the given column index.

-(int)numberColumns;

This call should return the number of columns to use on the layout.

##PrecalculatedHeightObject

A simple protocol with a single property to override

-(float)precalculatedHeight;

The property should return the height in pixels for this object in the layout.

Sample

See attached Xcode project (Sample was made with XCode 6.2)

License

MIT