iOS 从手机相册里选取图片

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

#import "AppDelegate.h"
#import "RootViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];

    UINavigationController *root = [[UINavigationController alloc] initWithRootViewController:[[RootViewController alloc] init]];
    self.window.rootViewController = root;

    [self.window makeKeyAndVisible];
    return YES;
}

@end

#import <UIKit/UIKit.h>

@interface RootViewController : UIViewController

@end

#import "RootViewController.h"

@interface RootViewController ()<UIActionSheetDelegate,UIImagePickerControllerDelegate,UINavigationControllerDelegate>

@property (strong, nonatomic) UIButton *btn;

@end

@implementation RootViewController

@synthesize btn;

- (void)loadView
{
    [super loadView];
    btn= [UIButton buttonWithType:UIButtonTypeCustom];
    btn.frame = CGRectMake(, , , );
    btn.backgroundColor = [UIColor purpleColor];
    [btn addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
}

- (void)btnAction:(UIButton *)sender
{
    UIActionSheet *actionsheet = [[UIActionSheet alloc] initWithTitle:nil delegate:self cancelButtonTitle:@"取消" destructiveButtonTitle:nil otherButtonTitles:@"从手机相册选取", nil];
    [actionsheet showInView:self.view];
}

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == ) {
        UIImagePickerController *imagepicker = [[UIImagePickerController alloc] init];
        imagepicker.delegate = self;
        imagepicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        imagepicker.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
        imagepicker.allowsEditing = YES;
        [self presentViewController:imagepicker animated:YES completion:^{}];
    }
}

#pragma amrk - 图片选择完成 -
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo
{
    [picker dismissViewControllerAnimated:YES completion:^{
        [btn setImage:image forState:];
    }];
}

@end