table view self sizing header

ProductCreateHeader.xib

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="7531" systemVersion="14D131" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES">
    <dependencies>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="7520"/>
    </dependencies>
    <customFonts key="customFonts">
        <mutableArray key="FreightSansPro-Book.otf">
            <string>FreightSansProBook-Regular</string>
        </mutableArray>
    </customFonts>
    <objects>
        <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner" customClass="ProductCreateViewController">
            <connections>
                <outlet property="header" destination="BIc-3s-nff" id="7kK-Rq-S7r"/>
                <outlet property="headerContent" destination="iN0-l3-epB" id="NzA-GC-9FM"/>
                <outlet property="headerLabel" destination="UWX-JG-lTJ" id="yNF-zg-B76"/>
            </connections>
        </placeholder>
        <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
        <view clipsSubviews="YES" contentMode="scaleToFill" id="BIc-3s-nff">
            <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
            <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
            <subviews>
                <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="iN0-l3-epB">
                    <rect key="frame" x="0.0" y="0.0" width="600" height="54"/>
                    <subviews>
                        <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Add ..." lineBreakMode="tailTruncation" numberOfLines="0" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="UWX-JG-lTJ">
                            <rect key="frame" x="8" y="15" width="584" height="24"/>
                            <fontDescription key="fontDescription" name="FreightSansProBook-Regular" family="FreightSans Pro" pointSize="19"/>
                            <color key="textColor" red="0.28529193997383118" green="0.28533676266670227" blue="0.28527560830116272" alpha="1" colorSpace="calibratedRGB"/>
                            <nil key="highlightedColor"/>
                        </label>
                    </subviews>
                    <color key="backgroundColor" white="0.33333333333333331" alpha="1" colorSpace="calibratedWhite"/>
                    <constraints>
                        <constraint firstItem="UWX-JG-lTJ" firstAttribute="leading" secondItem="iN0-l3-epB" secondAttribute="leading" constant="8" id="E2F-6d-j04"/>
                        <constraint firstAttribute="trailing" secondItem="UWX-JG-lTJ" secondAttribute="trailing" constant="8" id="GFX-Mw-LkS"/>
                        <constraint firstItem="UWX-JG-lTJ" firstAttribute="top" secondItem="iN0-l3-epB" secondAttribute="top" constant="15" id="KY3-t1-heO"/>
                        <constraint firstAttribute="bottom" secondItem="UWX-JG-lTJ" secondAttribute="bottom" constant="15" id="bY8-UW-XIq"/>
                    </constraints>
                </view>
            </subviews>
            <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
            <constraints>
                <constraint firstItem="iN0-l3-epB" firstAttribute="leading" secondItem="BIc-3s-nff" secondAttribute="leading" id="PyT-eZ-LYS"/>
                <constraint firstAttribute="bottom" secondItem="iN0-l3-epB" secondAttribute="bottom" id="Y7h-TG-ESO"/>
                <constraint firstItem="iN0-l3-epB" firstAttribute="top" secondItem="BIc-3s-nff" secondAttribute="top" id="YRR-WY-x3w"/>
                <constraint firstAttribute="trailing" secondItem="iN0-l3-epB" secondAttribute="trailing" id="hPs-1d-Xhj"/>
            </constraints>
            <variation key="default">
                <mask key="constraints">
                    <exclude reference="Y7h-TG-ESO"/>
                </mask>
            </variation>
            <point key="canvasLocation" x="329" y="831"/>
        </view>
    </objects>
</document>

ProductCreateViewController.m

// The header contains a super view (the container)
// and a headerContent. The headerContent is constrained to the top of the header (no bottom!)
// Also headerContent has constrains to specify it's height(e.g. a label that pushes).

@interface ProductCreateViewController()
@property (strong, nonatomic) IBOutlet UIView *headerContent;
@property (weak, nonatomic) IBOutlet UILabel *headerLabel;
@property (strong, nonatomic) IBOutlet UIView *header;

@end

@implementation ProductCreateViewController
@dynamic viewModel;

-(void)viewDidLoad{
  [super viewDidLoad];
  [[NSBundle mainBundle] loadNibNamed:@"ProductCreateHeader" owner:self options:nil];
  self.title = NSLocalizedString(@"Create",nil);
  self.headerLabel.text = @"asd asd aad asda dasd asd adasd asd ad asddasds dasd sadasd asda ds asd as dasd asd asd ";
  self.tableView.tableHeaderView = self.header;
}
-(void)viewDidLayoutSubviews{
  [super viewDidLayoutSubviews];
  [self.header setNeedsLayout];
  [self.header layoutIfNeeded];
  CGFloat height =  self.headerContent.frame.size.height;// adding the origin because innerHeaderView starts partway down headerView.
  CGRect frame = self.header.frame;
  frame.size.height = height;
  self.header.frame = frame;
  [self.tableView setTableHeaderView:self.header];
}@end