iOS应用打开pdf、doc、excel文件等

用WebView就可以完成。只描述一种，加载本地文件的代码：

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIWebView *webView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];    
    
    NSString *path = [[NSBundle
                       mainBundle] pathForResource:@"ipad.pdf"
                      ofType:nil];
    NSURL *url = [NSURL
                  fileURLWithPath:path];
    NSURLRequest *request = [NSURLRequest
                             requestWithURL:url];
    [self.webView
     loadRequest:request];
    
    
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end