UIImagePickerController使用方法

点击按钮后弹出图片库选择图片，然后返回给Button的image。

- (IBAction)selectIcon {
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc]init];
　　//设置图库源
    [imagePicker setSourceType:UIImagePickerControllerSourceTypePhotoLibrary];
　　//是否允许编辑图片
    [imagePicker setAllowsEditing:YES];
　　//设置当前控制器为代理
    [imagePicker setDelegate:self];
    [self presentViewController:imagePicker animated:YES completion:nil];
}

选取图片后需实现代理方法didFinishPickingMediaWithInfo

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    [_icon setImage:info[UIImagePickerControllerEditedImage] forState:UIControlStateNormal];
    [self dismissViewControllerAnimated:YES completion:nil];
}