//遵守协议

@interfaceViewController ()

@property(nonatomic,strong)UIButton *userBtn;

@end

@implementationViewController

- (void)viewDidLoad {

[superviewDidLoad];

//所有看得到的ui控件创建初始化方式都可以采用alloc initwithfram

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;

self.userBtn.layer.masksToBounds=YES;

//添加点击事件：去访问系统相册

[self.userBtn addTarget:selfaction:@selector(setUserImage) forControlEvents:(UIControlEventTouchUpInside)];

//将按钮添加到屏幕上来

[self.view addSubview:self.userBtn];

}

//访问系统相册

-(void)setUserImage

{

//创建系统相册

UIImagePickerController *imagePicker= [[UIImagePickerController alloc]init];

//设置代理，到@interface后面遵守协议

imagePicker.delegate=self;

//弹出系统相册

[selfpresentViewController:imagePicker animated:YEScompletion:nil];

}

//这个方法是协议UIImagePickerControllerDelegate里面的，选择图片结束的时候就会自动调用

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(nullableNSDictionary *)editingInfo

{

//设置头像

[self.userBtn setBackgroundImage:image forState:(UIControlStateNormal)];

//将系统相册消失掉

[picker dismissViewControllerAnimated:YEScompletion:nil];

}

- (void)didReceiveMemoryWarning {

[superdidReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}