使用Singleton类的全局变量NSMuteableArray [英] Global variable NSMuteableArray using Singleton Class
问题描述
我无法创建将集合传递给不同视图控制器的好方法。例如,我创建了一个名为Message的自定义类,其中包含许多属性。我希望有一个全局的NSMutableArray存储在一个名为消息的全局变量中,我可以添加到任何地方或从中获取。 Stackoverflow上的每个人都说不要使用你的delagate类存储全局变量,所以我创建了一个名为Shared的单例类。在那里,我为NSMutableArray创建了一个名为message的属性:
I'm having trouble creating a nice way of passing a collection around to different view controllers. For example, I created a custom class called Message with a bunch of attributes. I want to have a global NSMutableArray of those stored in a global variable of sorts called messages that I can add to or get from anywhere. Everyone on Stackoverflow says not to use your delagate class to store global variables so I created a singleton class called Shared. In there I created a property for the NSMutableArray called messages like this:
@interface Shared : NSObject {
}
@property (nonatomic, retain) NSMutableArray *messages;
+(Shared *) sharedInstance;
@end
我的.h文件是(重要部分) :
And my .h file is (the important part):
#import "Shared.h"
static Shared* sharedInstance;
@implementation Shared
@synthesize messages;
static Shared *sharedInstance = nil;
-(id) init {
self = [super init];
if (self != nil){
}
return self;
}
-(void) initializeSharedInstance {
}
+ (Shared *) sharedInstance{
@synchronized(self) {
if (sharedInstance == nil){
sharedInstance = [[self alloc] init];
[sharedInstance initializeSharedInstance];
}
return (sharedInstance);
}
}
在我的其他视图控制器中,我首先导入Shared.h,然后试试这个:
In my other view controller, I first import "Shared.h", then try this:
[[Shared sharedInstance].messages addObject:m];
NSLog([NSString stringWithFormat:@"Shared messages = %@", [Shared sharedInstance].messages]);
它保持打印null而不是m对象的集合。有什么想法?
It keeps printing null instead of the the collection of m objects. Any thoughts?
推荐答案
你需要一个静态变量。
在.h:
@interface Shared : NSObject
{
NSMutableArray *messages;
}
@property (nonatomic, retain) NSMutableArray *messages;
+ (Shared*)sharedInstance;
@end
in .m:
static Shared* sharedInstance;
@implementation Shared
@synthesize messages;
+ (Shared*)sharedInstance
{
if ( !sharedInstance)
{
sharedInstance = [[Shared alloc] init];
}
return sharedInstance;
}
- (id)init
{
self = [super init];
if ( self )
{
messages = [[NSMutableArray alloc] init];
}
return self;
}
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