如何查看NSString是否以某个其他字符串开头？

Question

我试图检查我将用作URL的字符串是否以http开头.我现在试图检查的方式似乎不起作用.这是我的代码:

NSMutableString *temp = [[NSMutableString alloc] initWithString:@"http://"];
if ([businessWebsite rangeOfString:@"http"].location == NSNotFound){
    NSString *temp2 = [[NSString alloc] init];
    temp2 = businessWebsite;
    [temp appendString:temp2];
    businessWebsite = temp2;
    NSLog(@"Updated BusinessWebsite is: %@", businessWebsite);
}

[web setBusinessWebsiteUrl:businessWebsite];

有任何想法吗？

Answer 1

试试这个:if ([myString hasPrefix:@"http"]).

顺便说一句,你的测试应该是!= NSNotFound代替== NSNotFound.但是说你的网址是ftp://my_http_host.com/thing,它会匹配,但不应该.

Answer 2

我喜欢用这个方法:

if ([[temp substringToIndex:4] isEqualToString:@"http"]) {
  //starts with http
}

甚至更容易:

if ([temp hasPrefix:@"http"]) {
    //do your stuff
}

Answer 3

如果您正在检查"http:",您可能需要不区分大小写的搜索:

NSRange prefixRange = 
    [temp rangeOfString:@"http" 
                options:(NSAnchoredSearch | NSCaseInsensitiveSearch)];
if (prefixRange.location == NSNotFound)