ios Initializer element is not a compile-time constant

在scope外进行静态变量声明，

static const CGRect CouponListViewRect = CGRectMake(0.0,0.0,0.0,0.0);

报错：

 Initializer element is not a compile-time constant

原理：

 

github上的回答：

42 down vote

When you define a variable outside the scope of a function, that variable's value is actually written into your executable file. This means you can only use a constant value. Since you don't know everything about the runtime environment at compile time (which classes are available, what is their structure, etc.), you cannot create objective c objects until runtime, with the exception of constant strings, which are given a specific structure and guaranteed to stay that way. What you should do is initialize the variable to nil and use +initialize to create your image. initialize is a class method which will be called before any other method is called on your class. Example: NSImage*imageSegment = nil;+(void)initialize {if(!imageSegment) imageSegment =[[NSImage alloc] initWithContentsOfFile:@"/User/asd.jpg"];}-(id)init {     self =[super init];     if(self){         // Initialization code here.     }     return self;}