indentationLevelForRowAtIndexPath not indenting custom cell

Yeah, it seems like custom table cells don’t do this automatically? You need to override the layoutSubviews method in the table cell class. See this question for how to do this.

This code worked perfectly for me (although be careful if you are setting a custom height w/ the delegate as well, they seem to interfere with each other):

- (void)layoutSubviews
{
    [super layoutSubviews];
    float indentPoints = self.indentationLevel * self.indentationWidth;

    self.contentView.frame = CGRectMake(
        indentPoints,
        self.contentView.frame.origin.y,
        self.contentView.frame.size.width - indentPoints, 
        self.contentView.frame.size.height
    );
}

Edit for iOS8 and later

The above does work for me on iOS, but it causes subtle bugs when trying to autosize the height of the cell as well. There is n easier solution: If you have autolayout turned for the cell just set the left margin of the contentView:

override func layoutSubviews() {
    super.layoutSubviews()
    self.contentView.layoutMargins.left = CGFloat(self.indentationLevel) * self.indentationWidth
    self.contentView.layoutIfNeeded()
}