Add cache control for iOS.

ios/FastImage/FFFastImageSource.h

@@ -7,6 +7,12 @@ typedef NS_ENUM(NSInteger, FFFPriority) {
     FFFPriorityHigh
 };
 
+typedef NS_ENUM(NSInteger, FFFCacheControl) {
+    FFFCacheControlImmutable,
+    FFFCacheControlWeb,
+    FFFCacheControlCacheOnly
+};
+
 // Object containing an image uri and metadata.
 @interface FFFastImageSource : NSObject
 
@@ -16,9 +22,12 @@ typedef NS_ENUM(NSInteger, FFFPriority) {
 @property (nonatomic) FFFPriority priority;
 // headers for the image request
 @property (nonatomic) NSDictionary *headers;
+// cache control mode
+@property (nonatomic) FFFCacheControl cacheControl;
 
 - (instancetype)initWithURL:(NSURL *)url
                    priority:(FFFPriority)priority
-                    headers:(NSDictionary *)headers;
+                    headers:(NSDictionary *)headers
+               cacheControl:(FFFCacheControl)cacheControl;
 
 @end

ios/FastImage/FFFastImageSource.m

@@ -5,12 +5,14 @@
 - (instancetype)initWithURL:(NSURL *)url
                    priority:(FFFPriority)priority
                     headers:(NSDictionary *)headers
+               cacheControl:(FFFCacheControl)cacheControl
 {
     self = [super init];
     if (self) {
         _url = url;
         _priority = priority;
         _headers = headers;
+        _cacheControl = cacheControl;
     }
     return self;
 }

ios/FastImage/FFFastImageView.m

@@ -114,6 +114,17 @@
                 break;
         }
         
+        switch (_source.cacheControl) {
+            case FFFCacheControlWeb:
+                options |= SDWebImageRefreshCached;
+                break;
+            case FFFCacheControlCacheOnly:
+                options |= SDWebImageCacheMemoryOnly;
+                break;
+            case FFFCacheControlImmutable:
+                break;
+        }
+        
         if (_onFastImageLoadStart) {
             _onFastImageLoadStart(@{});
             hasSentOnLoadStart = YES;

ios/FastImage/RCTConvert+FFFastImage.m

@@ -7,7 +7,13 @@ RCT_ENUM_CONVERTER(FFFPriority, (@{
                                    @"low": @(FFFPriorityLow),
                                    @"normal": @(FFFPriorityNormal),
                                    @"high": @(FFFPriorityHigh),
-}), FFFPriorityNormal, integerValue);
+                                   }), FFFPriorityNormal, integerValue);
+
+RCT_ENUM_CONVERTER(FFFCacheControl, (@{
+                                       @"immutable": @(FFFCacheControlImmutable),
+                                       @"web": @(FFFCacheControlWeb),
+                                       @"cacheOnly": @(FFFCacheControlCacheOnly),
+                                       }), FFFCacheControlImmutable, integerValue);
 
 + (FFFastImageSource *)FFFastImageSource:(id)json {
     if (!json) {
@@ -18,6 +24,7 @@ RCT_ENUM_CONVERTER(FFFPriority, (@{
     NSURL *uri = [self NSURL:uriString];
     
     FFFPriority priority = [self FFFPriority:json[@"priority"]];
+    FFFCacheControl cacheControl = [self FFFCacheControl:json[@"cache"]];
     
     NSDictionary *headers = [self NSDictionary:json[@"headers"]];
     if (headers) {
@@ -36,7 +43,7 @@ RCT_ENUM_CONVERTER(FFFPriority, (@{
         }
     }
     
-    FFFastImageSource *imageSource = [[FFFastImageSource alloc] initWithURL:uri priority:priority headers:headers];
+    FFFastImageSource *imageSource = [[FFFastImageSource alloc] initWithURL:uri priority:priority headers:headers cacheControl:cacheControl];
     
     return imageSource;
 }

src/index.js

@@ -39,7 +39,10 @@ class FastImage extends Component {
 
         if (fallback) {
             return (
-                <View style={[style, styles.imageContainer]} ref={this.captureRef}>
+                <View
+                    style={[style, styles.imageContainer]}
+                    ref={this.captureRef}
+                >
                     <FastImageView
                         {...props}
                         style={StyleSheet.absoluteFill}
@@ -87,11 +90,23 @@ FastImage.resizeMode = {
 }
 
 FastImage.priority = {
+    // lower than usual.
     low: 'low',
+    // normal, the default.
     normal: 'normal',
+    // higher than usual.
     high: 'high',
 }
 
+FastImage.cacheControl = {
+    // Ignore headers, use uri as cache key, fetch only if not in cache.
+    immutable: 'immutable',
+    // Respect http headers, no aggressive caching.
+    web: 'web',
+    // Only load from cache.
+    cacheOnly: 'cacheOnly',
+}
+
 FastImage.preload = sources => {
     FastImageViewNativeModule.preload(sources)
 }
@@ -104,6 +119,7 @@ const FastImageSourcePropType = PropTypes.shape({
     uri: PropTypes.string,
     headers: PropTypes.objectOf(PropTypes.string),
     priority: PropTypes.oneOf(Object.keys(FastImage.priority)),
+    cache: PropTypes.oneOf(Object.keys(FastImage.cacheControl)),
 })
 
 FastImage.propTypes = {