jQuery Nested Callbacks using Deferred Object

new.js

app.saveRows = function(obj) {
	var d = new $.Deferred(),
		count = obj.rows.length;
	$.each(obj.rows,function(i, row) {
		row.parentId = obj.id;
		$.post(otherURL,row,function(data2) {
			count--;
			$.when(app.saveImgs(row))
			.then(function() {
				if (count == 0) {
					d.resolve();
				}
			});
		});
	});
	return d.promise();
};

app.saveImgs = function(row) {
	var d = new $.Deferred(),
		count = row.imgs.length;
	$.each(row.imgs,function() {
		$.post(uploadURL,this,function() {
			count--;
			if (count == 0) {
				d.resolve();
			}
		});
	}
	return d.promise();
};

app.saveObj = function(obj) {
	$.when($.post(someURL,obj,function(data) { obj.id = data.id; }))
	.then(app.saveRows(obj))
	.then(app.renderObj(obj));
};

old.js

app.saveObj = function(obj) {
	obj.rowsToSave = obj.rows.length;
	$.post(someURL,obj,function(data) {
		$.each(obj.rows,function() {
			var row = this;
			row.parentId = data.id;
			obj.imgsToSave += row.imgs.length;
			$.post(otherURL,row,function(data2) {
				$.each(row.imgs,function() {
					this.rowId = data2.id;
					$.post(uploadURL,this,function() {
						obj.imgsToSave--;
						if (obj.imgsToSave == 0) {
							obj.rowsToSave--;
							if (obj.rowsToSave == 0) {
								app.renderObj(obj);
							}
						}
					});
				});
				if (row.imgs.length == 0) {
					obj.rowsToSave--;
					if (obj.rowsToSave == 0) {
						app.renderObj(obj);
					}
				}
			});
		});
	});
};