2015-09-11 16:07:18 -07:00

61 lines
2.6 KiB
Objective-C

/*
* Copyright (c) 2014-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
*/
#import <AsyncDisplayKit/ASLayoutable.h>
/** A layout spec is an immutable object that describes a layout, loosely inspired by React. */
@interface ASLayoutSpec : NSObject <ASLayoutable>
/**
Creation of a layout spec should only happen by a user in layoutSpecThatFits:. During that method, a
layout spec can be created and mutated. Once it is passed back to ASDK, the isMutable flag will be
set to NO and any further mutations will cause an assert.
*/
@property (nonatomic, assign) BOOL isMutable;
- (instancetype)init;
/**
* Set child methods
*
* Every ASLayoutSpec must act on at least one child. The ASLayoutSpec base class takes the
* reponsibility of holding on to the spec children. For a layout spec like ASInsetLayoutSpec that
* only requires a single child, the child can be added by calling setChild:.
*
* For layout specs that require a known number of children (ASBackgroundLayoutSpec, for example)
* a subclass should use the setChild to set the "primary" child. It can then use setChild:forIdentifier:
* to set any other required children. Ideally a subclass would hide this from the user, and use the
* setChildWithIdentifier: internally. For example, ASBackgroundLayoutSpec exposes a backgroundChild
* property that behind the scenes is calling setChild:forIdentifier:.
*
* Finally, a layout spec like ASStackLayoutSpec can take an unknown number of children. In this case,
* the setChildren: method should be used. For good measure, in these layout specs it probably makes
* sense to define setChild: to do something appropriate or to assert.
*/
- (void)setChild:(id<ASLayoutable>)child;
- (void)setChild:(id<ASLayoutable>)child forIdentifier:(NSString *)identifier;
- (void)setChildren:(NSArray *)children;
/**
* Get child methods
*
* There is a corresponding "getChild" method for the above "setChild" methods. If a subclass
* has extra layoutable children, it is recommended to make a corresponding get method for that
* child. For example, the ASBackgroundLayoutSpec responds to backgroundChild.
*
* If a get method is called on a spec that doesn't make sense, then the standard is to assert.
* For example, calling children on an ASInsetLayoutSpec will assert.
*/
- (id<ASLayoutable>)child;
- (id<ASLayoutable>)childForIdentifier:(NSString *)identifier;
- (NSArray *)children;
@end