[ios] NSCache 사용 방법

사용하는 것과 같은 방식으로 사용 NSMutableDictionary합니다. 차이점은 NSCache과도한 메모리 압력이 감지 되면 (즉, 너무 많은 값을 캐싱하는) 공간을 확보하기 위해 해당 값 중 일부를 해제한다는 것입니다.

인터넷에서 다운로드하거나 계산을 수행하여 런타임에 이러한 값을 다시 만들 수 있다면 NSCache필요에 맞을 수 있습니다. 데이터를 다시 만들 수없는 경우 (예 : 사용자 입력, 시간에 민감한 등) 데이터 NSCache가 파괴되므로에 저장해서는 안됩니다 .

예, 스레드 안전성을 고려하지 않음 :

// Your cache should have a lifetime beyond the method or handful of methods
// that use it. For example, you could make it a field of your application
// delegate, or of your view controller, or something like that. Up to you.
NSCache *myCache = ...;
NSAssert(myCache != nil, @"cache object is missing");

// Try to get the existing object out of the cache, if it's there.
Widget *myWidget = [myCache objectForKey: @"Important Widget"];
if (!myWidget) {
    // It's not in the cache yet, or has been removed. We have to
    // create it. Presumably, creation is an expensive operation,
    // which is why we cache the results. If creation is cheap, we
    // probably don't need to bother caching it. That's a design
    // decision you'll have to make yourself.
    myWidget = [[[Widget alloc] initExpensively] autorelease];

    // Put it in the cache. It will stay there as long as the OS
    // has room for it. It may be removed at any time, however,
    // at which point we'll have to create it again on next use.
    [myCache setObject: myWidget forKey: @"Important Widget"];
}

// myWidget should exist now either way. Use it here.
if (myWidget) {
    [myWidget runOrWhatever];
}

답변

@implementation ViewController
{
    NSCache *imagesCache;
}


- (void)viewDidLoad
{
    imagesCache = [[NSCache alloc] init];
}


// How to save and retrieve NSData into NSCache
NSData *imageData = [imagesCache objectForKey:@"KEY"];
[imagesCache setObject:imageData forKey:@"KEY"];

var cache = NSCache()
cache.setObject("String for key 1", forKey: "Key1")
var result = cache.objectForKey("Key1") as String
println(result) // Prints "String for key 1"

import Foundation

extension NSCache {
    class var sharedInstance : NSCache {
        struct Static {
            static let instance : NSCache = NSCache()
        }
        return Static.instance
    }
}

NSCache.sharedInstance.setObject("String for key 2", forKey: "Key2")
var result2 = NSCache.sharedInstance.objectForKey("Key2") as String
println(result2) // Prints "String for key 2"

[[CacheController storeInstance] setCache:@"object" forKey:@"objectforkey" ];

[[CacheController storeInstance] getCacheForKey:@"objectforkey" ];