iPhone - iPad Device Type Trick in the Header File

So I've got a function that really helps when I'm crafting device specific URLS but I'd like to place it in a global header file so any class could use it easily

- (NSString *)deviceType
{
    NSString *deviceName = @"iphone";
    if([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
    {
        if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){
            deviceName = @"ipad";
        }
        else {
            deviceName = @"iphone4";
        }
    }
    return deviceName;
}

That may or may not be the 开发者_如何学运维best way of doing it but I'd like to know how to get that into a global header so I can do something like this

NSString *deviceName = GETDEVICENAME;

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#define GETDEVICENAME [whatever deviceType] maybe?

There is an issue with your function though, on 3.2 UIScreen doesn't respond to scale (at least no publicly. I wouldn't rely on that to check for iPad.

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With in your project should be a file called %PROJECT%_Prefix.pch.

Any headers you include in that file will be accessible by all files in your project.

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Got the answer that worked for me,

In a global header file Globals.h I placed

NSString* deviceType();

in Globals.m I placed a modified function

NSString* deviceType()
{
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){
        return @"ipad";
    }
    else if([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
    {
        return @"iphone4";
    }
    else{
        return @"iphone";

    }
}