自定义外观的pikcerView，使用方法和UIPikcerView基本一致
- iOS 7.0+
- Xcode 6+
pod 'GWLCustomPiker'
import 'GWLCustomPiker.h'
GWLCustomPikerView *customPikerView = [[GWLCustomPikerView alloc]init];
customPikerView.frame = ?;
customPikerView.dataSource = ?;
customPikerView.delegate = ?; 
GWLCustomPiker is released under the MIT license. See LICENSE for details.