此 NSURL 请求已编译，但未按预期工作。我错过了什么？

Question

我目前正在学习iOS开发课程。我创建了一个基本的 Web 浏览器，可以处理输入的 URL，如果用户不添加它，它将添加"http://"。使用下面的代码，用户在textField中输入文本，应用程序加载一个网页。

我的任务是将带有空格textField条目视为Google搜索。当我运行我的应用程序时，它会加载网页，但 Google 搜索不起作用。我很困惑为什么，但我知道我可以放心，这是我做错了什么。问题是什么？

以下是属性：

// Properties
@property (nonatomic, strong) UIWebView *webView;
@property (nonatomic, strong) UITextField *textField;
@property (nonatomic, assign) BOOL isSearchTerm;

以下是我为测试textField是URL还是搜索词而编写BOOL：

// Test to determine whether textField.text is a searchTerm
- (BOOL)isSearchTerm:(UITextField *)textField {
    NSString *textInURLBar = textField.text;
    NSRange whiteSpaceRange = [textInURLBar rangeOfCharacterFromSet:[NSCharacterSet whitespaceCharacterSet]];
    if (whiteSpaceRange.location != NSNotFound) {
        return NO;
    } else {
        return YES;
    }
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    // Do a test of textField to see if it's a webpage or a search term
    if (self.isSearchTerm == YES) {
        // Homework: write code to searchGoogle, see method below
        [self searchGoogle:textField];
    } else {
        // isSearchTerm == NO, so treat as an URL
        NSString *URLString = textField.text;
        NSURL *URL = [NSURL URLWithString:URLString];
        // User enters incomplete URL
        if (!URL.scheme) {
            // if the user didn't enter http:// or https://
            URL = [NSURL URLWithString:[NSString stringWithFormat:@"http://%@", URLString]];
        }
        // User enters complete URL
        if (URL) {
            NSURLRequest *request = [NSURLRequest requestWithURL:URL];
            [self.webView loadRequest:request];
        }
    }
    return NO;
}

搜索谷歌的代码：

- (void)searchGoogle:(UITextField *)textField {
    NSString *URLString = textField.text;
    NSRange spaces = [URLString rangeOfString:@" "];
    NSString *searchTerm = [URLString stringByReplacingCharactersInRange:spaces withString:@"+"];
    // Google search query is http://www.google.com/search?q=
    NSURL *URL = [NSURL URLWithString:[NSString stringWithFormat:@"http://www.google.com/search?q=%@", searchTerm]];
    NSURLRequest *request = [NSURLRequest requestWithURL:URL];
    [self.webView loadRequest:request];
}

Answer 1

如果要

用+替换空格，则当前仅在第一次出现时执行此操作。您可能希望对所有匹配项执行此操作。因此，您可以使用 stringByReplacingOccurrencesOfString:withString: 而不是 stringByReplacingCharactersInRange 。

或者，您可能希望对输入进行百分比转义（不仅要处理空格，还要处理其他保留字符）。Web 浏览器倾向于为您执行此操作，但是在自己创建请求时，您必须在代码中手动执行此操作。因此，至少您可以使用stringByAddingPercentEscapesUsingEncoding创建新字符串（代替stringByReplacingCharactersInRange）。

从技术上讲，您可能希望进一步完善 google 逻辑（执行百分比转义，用 + 个字符替换空格，但正确百分比转义字符，上述字符不会）您需要比stringByAddingPercentEscapesUsingEncoding本身执行的字符数），因此您将对添加到 google 查询的值（但不是 URL 本身）执行以下百分比转义：

- (NSString *)percentEscapeString:(NSString *)string
{ 
    NSString *result = CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,
                                                                                 (CFStringRef)string,
                                                                                 (CFStringRef)@" ",
                                                                                 (CFStringRef)@":/?@!$&'()*+,;=",
                                                                                 kCFStringEncodingUTF8));
    return [result stringByReplacingOccurrencesOfString:@" " withString:@"+"];
}

Answer 2

它并不漂亮，但我让它工作了。我取出了BOOL和googleSearch功能，并将所有内容都倾倒在textFieldShouldReturn中.

与其将一堆代码转储到textFieldShouldReturn中，我想将其分解为更可重用的代码（有效）。虽然它有效，但我认为它很丑陋。

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    NSString *URLString = textField.text;
    // This is if it's a normal request
    if ([URLString rangeOfString:@" "].location == NSNotFound) {
        NSURL *URL = [NSURL URLWithString:URLString];
        // User enters incomplete URL
        if (!URL.scheme) {
            // if the user didn't enter http:// or https://
            URL = [NSURL URLWithString:[NSString stringWithFormat:@"http://%@", URLString]];
        }
        // User enters complete URL
        if (URL) {
            NSURLRequest *request = [NSURLRequest requestWithURL:URL];
            [self.webView loadRequest:request];
        }
    }
    // This handles a space in the textField.text
    if ([URLString rangeOfString:@" "].location != NSNotFound) {
        NSLog(@"there's a space in the request");
        URLString = [URLString stringByReplacingOccurrencesOfString:@" " withString:@"+"];
        NSLog(@"The new URLString is %@", URLString);
        NSURL *URL = [NSURL URLWithString:URLString];
        // User enters incomplete URL
        if (!URL.scheme) {
            // if the user didn't enter http:// or https://
            URL = [NSURL URLWithString:[NSString stringWithFormat:@"http://google.com/search?q=%@", URLString]];
        }
        // User enters complete URL
        if (URL) {
            NSURLRequest *request = [NSURLRequest requestWithURL:URL];
            [self.webView loadRequest:request];
        }
    }
    return NO;
}