initWithSpriteFrameName和createWithSpriteFrameName

/**
     * Initializes a sprite with a sprite frame name. <br/>
     * A cc.SpriteFrame will be fetched from the cc.SpriteFrameCache by name.  <br/>
     * If the cc.SpriteFrame doesn't exist it will raise an exception. <br/>
     * @param {String} spriteFrameName A key string that can fected a volid cc.SpriteFrame from cc.SpriteFrameCache
     * @return {Boolean} true if the sprite is initialized properly, false otherwise.
     * @example
     * var sprite = new cc.Sprite();
     * sprite.initWithSpriteFrameName("grossini_dance_01.png");
     */
    initWithSpriteFrameName:function (spriteFrameName) {
        cc.Assert(spriteFrameName != null, "");
        var frame = cc.SpriteFrameCache.getInstance().getSpriteFrame(spriteFrameName);
        return this.initWithSpriteFrame(frame);
    },

/**
 * <p>
 *     Creates a sprite with a sprite frame.                                                                  <br/>
 *                                                                                                            <br/>
 *    A CCSpriteFrame will be fetched from the CCSpriteFrameCache by pszSpriteFrameName param.                <br/>
 *    If the CCSpriteFrame doesn't exist it will raise an exception.
 * </p>
 * @param {String} spriteFrameName A sprite frame which involves a texture and a rect
 * @return {cc.Sprite} A valid sprite object
 * @example
 *
 * //create a sprite with a sprite frame
 * var sprite = cc.Sprite.createWithSpriteFrameName('grossini_dance_01.png');
 */
cc.Sprite.createWithSpriteFrameName = function (spriteFrameName) {
    var spriteFrame = null;
    if (typeof(spriteFrameName) == 'string') {
        spriteFrame = cc.SpriteFrameCache.getInstance().getSpriteFrame(spriteFrameName);
        if (!spriteFrame) {
            cc.log("Invalid spriteFrameName: " + spriteFrameName);
            return null;
        }
    } else {
        cc.log("Invalid argument. Expecting string.");
        return null;
    }
    var sprite = new cc.Sprite();
    if (sprite && sprite.initWithSpriteFrame(spriteFrame)) {
        return sprite;
    }
    return null;
};