Databases
StackOverflow2013
Postsdbo
POHow to safely read properties of a WebScriptObject?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to safely read properties of a WebScriptObject?
    primarykey
    data
    text
    <p>When communicating between JavaScript in a <code>WebView</code> instance and a <code>WebViewDelegate</code>, JavaScript types and Objective-C types are converted back and forth. For instance, when calling an Objective-C function from JavaScript, a string becomes an <code>NSString</code>, a number becomes an <code>NSNumber</code>, and an Object becomes a <code>WebScriptObject</code>.</p> <p>The others are pretty simple to deal with, but <code>WebScriptObject</code> seems weird.</p> <p>When passing a dictionary like <code>{"foo": 1, "bar": 2}</code>, most of the code I see extracts the properties using <code>valueForKey</code>, such as in <code>[[arg valueForKey:@"foo"] intValue] == 1</code></p> <p>But what about if you're not sure if the property exists? What if the keys are optional? <code>[arg valueForKey:@"baz"]</code> throws an exception.</p> <p>One thing I can do is something like</p> <pre><code>@try { foo = [[arg valueForKey:@"baz"] intValue]; } @catch (NSException* e) { foo = 0; } </code></pre> <p>but I've heard that exceptions in Objective-C are unsafe and should not be used for flow control.</p> <p>The only other way I can think of is some variation of the method used here: <a href="http://edotprintstacktrace.blogspot.com/2011/10/sample-webscriptobject-javascript.html">http://edotprintstacktrace.blogspot.com/2011/10/sample-webscriptobject-javascript.html</a></p> <p>In other words: 1. use <code>evaluateWebScript</code> to define a JavaScript function that implements <code>Object.keys</code> 2. call that function on your <code>WebScriptObject</code> 3. iterate through the returned array of keys, and only call <code>valueForKey</code> if we find a match.</p> <p>This seems incredibly inefficient, to me. There must be a better way... is there?</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USZarel
    1. USZarel
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to safely read properties of a WebScriptObject?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow to safely read properties of a WebScriptObject?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POHow to safely read properties of a WebScriptObject?
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload