//遵守协议
@interface ViewController ()<UINavigationControllerDelegate, UIImagePickerControllerDelegate>
@property(nonatomic,strong)UIButton *userbtn;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
//所有能看得到的UI控件创建初始化方式都可以采用alloc initWithFrame
self.userbtn=[[UIButton alloc]initWithFrame:CGRectMake(30, 60, 80, 80)];
//设置颜色
self.userbtn.backgroundColor=[UIColor redColor];
//设置圆形半径
self.userbtn.layer.cornerRadius = 40;
//超过内切圆的部分是否切割掉
self.userbtn.layer.masksToBounds=YES;
//添加点击事件：去访问系统相册
[self.userbtn addTarget:self action:@selector(setuserimage) forControlEvents:(UIControlEventTouchUpInside)];
//将按钮添加到屏幕上
[self.view addSubview:self.userbtn];}
-(void)steuserimage{
//创建系统相册
UIImagePickerController *imagePicker=[[UIImagePickerController alloc]init];
//设置代理，到@interface后面遵守协议<UINavigationControllerDelegate, UIImagePickerControllerDelegate>
imagePicker.delegate=self;
//弹出系统相册
[self presentViewController:imagePicker animated:YES completion:nil]; }
//这个方法是协议UIImagePickerControllerDelegate里面的，选择图片结束就会自动调用
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(nullable NSDictionary*)editingInfo{
//设置头像
[self.userbtn setBackgroundImage:image forState:(UIControlStateNormal)];
//将系统相册消失掉
[picker dismissViewControllerAnimated:YES completion:nil];
}
