Objective c 检查包含“URL”的字符串；http://quot；

我试图检查用户输入的URL，但我正在与一些错误和警告作斗争

-(BOOL) textFieldShouldReturn:(UITextField *)textField {
    //check "http://"
    NSString *check = textField.text;
    NSString *searchString = @"http://";
    NSRange resultRange = [check rangeWithString:searchString];
    BOOL result = resultRange.location != NSNotFound;
    if (result) {
        NSURL *urlAddress = [NSURL URLWithString: textField.text];
    } else {
        NSString *good = [NSString stringWithFormat:@"http://%@", [textField text]];
        NSURL *urlAddress = [NSURL URLWithString: good];
    }
    // open url
    NSURLRequest *requestObject = [NSURLRequest requestWithURL:urlAddress];
}

他们说：

NSString

可能不会响应

-rangeWithString

在“if…else”条件下未使用的变量

urldaddress

（用于两者）

urlAddress

未声明：在

URLRequest

---

有人知道该怎么办吗？

我相信你想要这个方法。

要摆脱你的

urlAddress

警告，你应该在上面声明

NSURL*urlAddress

if..else

：

NSURL *urlAddress = nil;
if (result) {  
    urlAddress = [NSURL URLWithString: textField.text];    
} else {   
    NSString *good = [NSString stringWithFormat:@"http://%@", [textField text]];  
    urlAddress = [NSURL URLWithString: good];     
}   

---

NSString响应

rangeOfString:

，而不是

rangeWithString:

变量urlAddress在

if

语句和

else

语句中声明。这意味着它只存在于这个范围内。离开if/else语句后，变量就消失了

对于URL，最好是以方案开头（如“http:/”），您的代码将乐于接受apple。http://.com 因为它是有效的

您可以改用

hasPrefix:

方法，如下所示：

BOOL result = [[check lowercaseString] hasPrefix:@"http://"];
NSURL *urlAddress = nil;

if (result) {  
    urlAddress = [NSURL URLWithString: textField.text];
}
else {
    NSString *good = [NSString stringWithFormat:@"http://%@", [textField text]];
    urlAddress = [NSURL URLWithString: good];
}

NSURLRequest *requestObject = [NSURLRequest requestWithURL:urlAddress];

---

如果有NSURL，请使用将其转换为NSString

   NSString stringURL = url.absoluteString

然后用此代码检查此NSString是否包含http://

 [stringURL containsString: @"http://"]


    - (BOOL)containsString:(NSString *)string {
    return [self containsString:string caseSensitive:NO];
}

- (BOOL)containsString:(NSString*)string caseSensitive:(BOOL)caseSensitive {
    BOOL contains = NO;
    if (![NSString isNilOrEmpty:self] && ![NSString isNilOrEmpty:string]) {
        NSRange range;
        if (!caseSensitive) {
            range =  [self rangeOfString:string options:NSCaseInsensitiveSearch];
        } else {
            range =  [self rangeOfString:string];
        }
        contains = (range.location != NSNotFound);
    }

    return contains;
}

用这个

NSString *stringUrl = url.absoluteString;

if ([stringUrl localizedCaseInsensitiveContainsString:@"your string"]) {
    //do something
}

---

它首先将url转换为字符串，然后检查此url是否包含您的字符串

最好使用[stringUrl localizedCaseInsensitiveContainsString:@“gif”]

NSString *stringUrl = url.absoluteString;

if ([stringUrl localizedCaseInsensitiveContainsString:@"your string"]) {
    //do something
}