cocoa - 在 Cocoa 的不同函数中保留随机数？

Question

我知道如何创建全局变量，但是每当我尝试使用随机数函数定义全局变量时，xcode 都会显示“初始化元素不是常量”。编译器不想从随机数创建变量，因为随机数函数不是常数。

如何生成一个随机数，然后将同一值用于多个操作？ (例如，定义颜色然后将该值写入标签？)

代码:

#import "Slider_with_IBAppDelegate.h"

float * const hue = ((arc4random() % ((unsigned)100 + 1))/100.0);

//^this is where I get the error: "initializer element is not constant"

@synthesize label

//write value to label
- (IBAction) doButton {
label.text = [NSString stringWithFormat:@"%f", hue];
}

//set background color
- (void)applicationDidBecomeActive:(UIApplication*)application
{
self.label5.backgroundColor = [UIColor colorWithHue:hue                        
                                             saturation:1.0                                      
                                             brightness:1.0                                       
                                                  alpha:1.0];
}

----编辑------

感谢您的建议。但它仍然对我不起作用，我做错了什么？

新代码:

#import "Slider_with_IBAppDelegate.h"

float const hue = ((arc4random() % ((unsigned)100 + 1))/100.0);

//^I still get the error: "initializer element is not constant."

@synthesize label

//write value to label
- (IBAction) doButton {
label.text = [NSString stringWithFormat:@"%f", hue];
}  
//^this is where I get the error "'hue' undeclared (first use of this function)"

//set background color
- (void)applicationDidBecomeActive:(UIApplication*)application
{

hue = ((arc4random() % ((unsigned)1000 + 1))/1000.0);
/*here I get the error "assignment of read-only variable 'hue.'"  
If I insert "float" just before hue, I do not get this error, 
but it still won't compile because of the error above.*/

self.label5.backgroundColor = [UIColor colorWithHue:hue                        
                                         saturation:1.0                                         
                                         brightness:1.0                                          
                                              alpha:1.0];
}

Answer 1

将其设为非常量并在 applicationDidBecomeActive 中对其进行初始化。有什么理由它必须保持不变吗？