feature: add function setupFilters for GPUImageFilterGroup

framework/Source/GPUImageFilterGroup.h

@@ -1,6 +1,8 @@
 #import "GPUImageOutput.h"
 #import "GPUImageFilter.h"
 
+typedef GPUImageOutput<GPUImageInput> FilterOutputType;
+
 @interface GPUImageFilterGroup : GPUImageOutput <GPUImageInput>
 {
     NSMutableArray *filters;
@@ -11,6 +13,8 @@
 @property(readwrite, nonatomic, strong) NSArray *initialFilters;
 @property(readwrite, nonatomic, strong) GPUImageOutput<GPUImageInput> *inputFilterToIgnoreForUpdates; 
 
++ (instancetype)filterGroupWithFilters:(NSArray <FilterOutputType *> *)filters;
+
 // Filter management
 - (void)addFilter:(GPUImageOutput<GPUImageInput> *)newFilter;
 - (GPUImageOutput<GPUImageInput> *)filterAtIndex:(NSUInteger)filterIndex;

framework/Source/GPUImageFilterGroup.m

@@ -19,6 +19,22 @@ - (id)init;
     return self;
 }
 
++ (instancetype)filterGroupWithFilters:(NSArray <FilterOutputType *> *)filters {
+    if (filters.count == 0) {
+        return nil;
+    }
+
+    GPUImageFilterGroup *filterGroup = [[GPUImageFilterGroup alloc] init];
+    for (FilterOutputType *filter in filters) {
+        [filterGroup addFilter:filter];
+    }
+
+    [filterGroup setInitialFilters:filters];
+    [filterGroup setTerminalFilter:filters.lastObject];
+
+    return filterGroup;
+}
+
 #pragma mark -
 #pragma mark Filter management