Assign Enum to Variable in Objective-C

Question

How can I assign an enum to a variable and access its value later? I thought this would be pretty simple, but every time I try to assign the enum value to a variable (no type mismatches or warnings in Xcode appear) my app crashes with an EXC_BAD_ACCESS error.

Here's how I setup my enum in my header file (BarTypes.h):

typedef enum {
    BarStyleGlossy,
    BarStyleMatte,
    BarStyleFlat
} BarDisplayStyle;

No issues there (reading and using the values at least). However, when I create a variable that can store one of the enum values (BarStyleGlossy, BarStyleMatte, or BarStyleFlat) then try to set that variable, the app crashes. Here's how I setup and use the variable:

//Header
@property (nonatomic, assign, readwrite) BarDisplayStyle barViewDisplayStyle; //I've also tried just using (nonatomic) and I've also tried (nonatomic, assign)

//Implementation
@synthesize barViewDisplayStyle;

- (void)setupBarStyle:(BarDisplayStyle)displayStyle {
    //This is where it crashes:
    self.barViewDisplayStyle = displayStyle;
}

Why is it crashing here? How do I store the value of an enum in a variable? I think the issue has to do with a lack of understanding about enums on my end, however if I follow conventional variable setup and allocation, etc. this should work. Any ideas on what I'm doing wrong?

Please note that I'm new to enums, so my vocabulary here may be a bit mixed up (forgive me - and feel free to make an edit if you know what I'm trying to say).

I found a few references about enums across the web:

What is a typedef enum in Objective-C?
Using enum types as properties in Objective C
How to create global enum
How do I define and use an ENUM in Objective-C?
I also tried searching Apple's Developer site but only came up with results about types for Apple APIs (ex. Foundation, UIKit, etc.)

EDIT: Here's how I call the setupBarStyle method:

BarView *bar = [[BarView alloc] init];
[bar setupBarStyle:displayStyle];

Compiled and ran your code without any crash. Please add a crash log. — Guillaume Algis
– Guillaume Algis, Commented Jun 5, 2013 at 21:24

Gwenc37 · Accepted Answer · 2014-05-06 14:18:43Z

10

Just in case anyone out there is still trying to figure out how to assign an enum value to an enum typed variable or property... Here is an example using a property.

In the header file...

@interface elmTaskMeasurement : NSObject

typedef NS_ENUM(NSInteger, MeasurementType) {
    D,
    N,
    T,
    Y,
    M
};

@property(nonatomic) MeasurementType MeasureType;

@end

In the file where the object is created...

elmTaskMeasurement *taskMeasurement = [[elmTaskMeasurement alloc] init];

taskMeasurement.MeasureType = (MeasurementType)N;

edited May 6, 2014 at 14:18

Gwenc37

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answered May 6, 2014 at 14:01

user3608568

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Comments

user529758 · Accepted Answer · 2013-06-05 21:02:00Z

0

The method you implement is called setupBarStyle:, but you call setupBarShape: on the object.

answered Jun 5, 2013 at 21:02

user529758

2 Comments

Sam Spencer Over a year ago

Sorry, I made a typo transferring the method call to my question. I've fixed it now

user529758 Over a year ago

@RazorSharp (I always wonder how possibly copy-paste can cause such typos...)

Tom Vos · Accepted Answer · 2015-04-30 08:05:42Z

0

I had this error myself but the error was caused by a different bug I off course create myself.

The setter of my property "myApplicationState" was as follows:

-(void)setApplicationStyle:(myApplicationStyle)applicationStyle{
    self.applicationStyle = applicationStyle;
    //some more code
}

Off course this would result in an endless loop because in the setter, the setting is called again, and again, and again.

It had to be:

-(void)setApplicationStyle:(myApplicationStyle)applicationStyle{
    _applicationStyle = applicationStyle;
    //some more code
}

answered Apr 30, 2015 at 8:05

Tom Vos

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