访问系统相册

//遵守协议

@interface ViewController ()

@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

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];

}