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, Jun 05 '13 at 21:24

score 10 · Accepted Answer · edited May 06 '14 at 14:18

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;

score 0 · Answer 2 · answered Jun 05 '13 at 21:02

0

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

answered Jun 05 '13 at 21:02

Sorry, I made a typo transferring the method call to my question. I've fixed it now – Sam Spencer Jun 05 '13 at 21:02
1

@RazorSharp (I always wonder how possibly copy-paste can cause such typos...) – Jun 05 '13 at 21:03

score 0 · Answer 3 · answered Apr 30 '15 at 08:05

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
}

Assign Enum to Variable in Objective-C

3 Answers3