How to get a class's property from a string?

Question

I want to get a class's property from a string. For example:

    NSString * propertyStr = @"propertyStr";
    if ([class haveProperty:propertyStr]) {
        class.propertyStr = @"avalue";
    }

I don't know if i have say it clear.

http://stackoverflow.com/questions/6615826/get-property-name-as-a-string — Tirth, Dec 12 '13 at 06:53

Anoop Vaidya · Answer 1 · 2013-12-13T08:06:41.520

4

You want to check if your class have property called propertyStr, for that you can do :

NSString *propertyStr = @"propertyStr";
if ([class respondsToSelector:NSSelectorFromString(propertyStr)]) {
    class.propertyStr = @"avalue";
}

edited Dec 13 '13 at 08:06

answered Dec 12 '13 at 06:53

Anoop Vaidya

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Just updated `if ([class respondsToSelector:NSSelectorFromString(propertyStr)])` it was `if ([self respondsToSelector:NSSelectorFromString(propertyStr)])` – Maulik Dec 12 '13 at 07:07
First thank you.And how to judge the property is NSString or int? – Dracuuula Dec 12 '13 at 07:23
objective-c runtime is one way to check – Anoop Vaidya Dec 12 '13 at 07:57

score 2 · Accepted Answer · answered Dec 12 '13 at 06:55

2

Since @property and @syn automatically create the getter and setters we can use the below code to check if any class responds to particular message (setter)

NSString *propertyStr = @"propertyStr";
if ([class respondsToSelector:NSSelectorFromString(propertyStr)]) 
{
[class setValue:@"Value" forKey:propertyStr];
}

answered Dec 12 '13 at 06:55

Gyanendra Singh

1,483
12
15

First thank you.And how to judge the property is NSString or int? – Dracuuula Dec 12 '13 at 07:25
You can check using if([class.propertyStr isKindOfClass[NSString Class]])// Then set the value accordingly otherwise else condition... – Gyanendra Singh Dec 12 '13 at 07:48
primitives are not subClass of NSObject, hence `isKindOfClass` will not work, will be an compiler error. [Check this answer](http://stackoverflow.com/questions/20537787/how-to-know-the-type-of-classs-property-from-string/20538879#20538879) – Anoop Vaidya Dec 13 '13 at 08:05

score 1 · Answer 3 · answered Dec 12 '13 at 06:51

1

Try with respondsToSelector

Syntax

 if ([class respondsToSelector:@selector(property)])
        [[class property] setProperty:@"value"];

Example

if ([UINavigationBar respondsToSelector:@selector(appearance)])
    [[UINavigationBar appearance] setBarStyle:UIBarStyleBlackOpaque];

answered Dec 12 '13 at 06:51

he wants to access through the string, not directly from the property. So your answer doesn't help him, but I wonder upvotes :D – Anoop Vaidya Dec 12 '13 at 06:57
@Virussmca: do you give upvote only becuase of first answer or to correct answer? – Anoop Vaidya Dec 12 '13 at 06:58
@AnoopVaidya: i gave sample way that show that is class has property to or not./ – Dec 12 '13 at 06:59
@AnandVyas: But your sample way is not the answer he is asking. – Anoop Vaidya Dec 12 '13 at 07:00
@AnoopVaidya: i just help him to check that it has property or not. – Dec 12 '13 at 07:01

score 1 · Answer 4 · answered Dec 12 '13 at 06:55

1

You can try this..

NSString *selName = @"yourPropertyName";
SEL selector = NSSelectorFromString(selName);

if ([className respondsToSelector:selector])
    className.selName = /* your action*/;

answered Dec 12 '13 at 06:55

Mani

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How to get a class's property from a string?

4 Answers4