Retrieve custom prototype cell height from storyboard?

Question

When using \"Dynamic Prototypes\" for specifying UITableView content on the storyboard, there is a \"Row Height\" property that can be set to Custom.

Wh

Answer 1

I created a category for UITableView some time ago that may come helpful for this. It stores 'prototype' cells using asociated objects for reusing the prototypes and provides a convenience method for obtaining the height of the row assigned in storyboard. The prototypes are released when the table view is deallocated.

UITableView+PrototypeCells.h

#import 

@interface UITableView (PrototypeCells)

- (CGFloat)heightForRowWithReuseIdentifier:(NSString*)reuseIdentifier;
- (UITableViewCell*)prototypeCellWithReuseIdentifier:(NSString*)reuseIdentifier;

@end

UITableView+PrototypeCells.m

#import "UITableView+PrototypeCells.h"
#import 

static char const * const key = "prototypeCells";

@implementation UITableView (PrototypeCells)
- (void)setPrototypeCells:(NSMutableDictionary *)prototypeCells {
    objc_setAssociatedObject(self, key, prototypeCells, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (NSMutableDictionary *)prototypeCells {
    return objc_getAssociatedObject(self, key);
}

- (CGFloat)heightForRowWithReuseIdentifier:(NSString*)reuseIdentifier {
    return [self prototypeCellWithReuseIdentifier:reuseIdentifier].frame.size.height;
}

- (UITableViewCell*)prototypeCellWithReuseIdentifier:(NSString*)reuseIdentifier {
    if (self.prototypeCells == nil) {
        self.prototypeCells = [[NSMutableDictionary alloc] init];
    }

    UITableViewCell* cell = self.prototypeCells[reuseIdentifier];
    if (cell == nil) {
        cell = [self dequeueReusableCellWithIdentifier:reuseIdentifier];
        self.prototypeCells[reuseIdentifier] = cell;
    }
    return cell;
}

@end

Usage

Obtaining the static height set in storyboard is as simple as this:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    return [tableView heightForRowWithReuseIdentifier:@"cellIdentifier"];
}

Assuming a multi-section table view:

enum {
    kFirstSection = 0,
    kSecondSection
};

static NSString* const kFirstSectionRowId = @"section1Id";
static NSString* const kSecondSectionRowId = @"section2Id";

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    CGFloat height = tableView.rowHeight; // Default UITableView row height
    switch (indexPath.section) {
        case kFirstSection:
            height = [tableView heightForRowWithReuseIdentifier:kFirstSectionRowId];
            break;
        case kSecondSection:
            height = [tableView heightForRowWithReuseIdentifier:kSecondSectionRowId];
    }
    return height;
}

And finally if the row height is dynamic:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    id thisRowData = self.allData[indexPath.row]; // Obtain the data for this row

    // Obtain the prototype cell
    MyTableViewCell* cell = (MyTableViewCell*)[self prototypeCellWithReuseIdentifier:@"cellIdentifier"];

    // Ask the prototype cell for its own height when showing the specified data
    return [cell heightForData:thisRowData];
}