Iphone – Smooth scaling when adding/removing subviews to/from a UIView

iphoneuikituiview

I'm using a subclass of a UIView to (programmatically) contain and manage numerous subviews (mostly UIImageViews) that are to be positioned adjacent to each other such that none are overlapping. It's safe to assume that the subviews are all the same height (when originally drawn), but are varying widths. The container might be resized, in which case I want the subviews to be scaled proportionally. Moreover, there are times when I need to add/remove/edit any given subview (which might change its width).

I'm had some success in using:

[self setAutoresizesSubviews:YES];
[self setAutoresizingMask:(UIViewAutoresizingFlexibleLeftMargin  |
                               UIViewAutoresizingFlexibleWidth       |
                               UIViewAutoresizingFlexibleRightMargin |
                               UIViewAutoresizingFlexibleTopMargin   |
                               UIViewAutoresizingFlexibleHeight      |
                               UIViewAutoresizingFlexibleBottomMargin)];

to have the container automatically resize its subviews when its frame changes.

Unfortunately, I'm having a lot of trouble dealing with the case when the contents of a subview changes, causing it to widen or contract. Simply setting 'setNeedsLayout' and defining 'layoutSubviews' for the subview doesn't seem to do the trick because, at the beginning of 'layoutSubviews' the subview's frame hasn't been adjusted. If I force it, then the current contents are stretched or contracted, which looks terrible.

I'd certainly appreciate it if someone could explain how sizeToFit, layoutSubviews, sizeThatFits:, setAutoresizesSubviews:, setAutoresizingMask:, and setContentMode: should be used in a case like this. I mean, if I want to adjust the contents of a subview (and widen it), then how do I do it such that:

the subview is widened (without adversely stretching or autoresizing anything else within it)
the container is widened a proportional amount
none of the other subviews are affected

Thanks in advance!

Best Answer

I ended up going the manual route, using sizeThatFits: and layoutSubviews to explicitly control how everything was redrawn and organized. I found that setAutoresizesSubviews: and setAutoresizingMask: helped for simple layouts, but that it was hard to debug if I tried anything even slightly atypical.

My advice: the first time you're experimenting with programmatic layouts define sizeThatFits for all of your (sub) views and define layoutSubviews for each. Use debugging statements to log the placement of everything. Once you're happy, consider incorporating autoresizing to simply your code (if possible).

Related Solutions

.net – Client side validation for custom annotation Asp.Net MVC 4

That article is specific to MVC 2 which used MicrosoftAjax. MVC 4 no longer includes the MS Ajax files as they have been deprecated and the preferred method is to use jquery.

To verify your settings, make sure these scripts are in your layout

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>

And these two settings are present in the appSettings section in your web.config file

<add key="ClientValidationEnabled" value="true"/>
<add key="UnobtrusiveJavaScriptEnabled" value="true"/>

So when you add data annotations to your ViewModels you get client side and server side validation both

public class MyModel 
{
    [Required]
    [StringLength(30)]
    public string FirstName { get; set; }

    [Required]
    [StringLength(30)]
    public string LastName { get; set; }
}

In your view just make sure you have code like this

<div>
    @Html.LabelFor(model => model.FirstName)
</div>
<div>
    @Html.TextBoxFor(model => model.FirstName) <br/>
    @Html.ValidationMessageFor(model => model.FirstName)
</div>

<div>
    @Html.LabelFor(model => model.LastName)
</div>
<div>
    @Html.TextBoxFor(model => model.LastName) <br/>
    @Html.ValidationMessageFor(model => model.LastName)
</div>

Update

Here's an example of a custom validator that I have called RateRequiredIfCustomIndexRate This is the javascript side of it so that it gets added to jquery validation

$("document").ready(function () {

    var isCustomRateRequired = document.getElementById("IsCustomRateRequired");

    isCustomRateRequired.onchange = function () {
        if (this.checked) {
            $('#Rate').attr('disabled', 'disabled');
            $('#Rate').val('');
        }
        else {
            $('#Rate').removeAttr('disabled');
        }
    };
});

jQuery.validator.addMethod("raterequiredifcustomindexrate", function (value, element, param) {
    var rateRequired = $("#CustomRateRequired").val();
    if (rateRequired && value == "") {
        return false;
    }
    return true;
});

jQuery.validator.unobtrusive.adapters.addBool("raterequiredifcustomindexrate");

Ios – Creating a reusable UIView with xib (and loading from storyboard)

Note that this QA (like many) is really just of historic interest.

~~Nowadays~~ For years and years now in iOS everything's just a container view. Full tutorial here

(Indeed Apple finally added Storyboard References, some time ago now, making it far easier.)

Here's a typical storyboard with container views everywhere. Everything's a container view. It's just how you make apps.

enter image description here

(As a curiosity, KenC's answer shows exactly how, it used to be done to load an xib to a kind of wrapper view, since you can't really "assign to self".)

Best Answer

Related Solutions

.net – Client side validation for custom annotation Asp.Net MVC 4

Ios – Creating a reusable UIView with xib (and loading from storyboard)

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