Question

我是Objective-c的新手让我们假设我有一个像这样的字符串

NSString* s = @"assets-library://asset/asset.MOV? id=100000009&ext=MOV"

如何从中获取“ext =”（本例中为“MOV”）的内容？我怎么把它转换成大写（所以“mov” - ＆gt;“MOV”），以防它还没有呢？

Answer 1

您可以使用NSString componentsSeparatedByString方法将字符串分解为数组：

NSString *sourceString = @"assets-library://asset/asset.MOV? id=100000009&amp;ext=MOV";
NSArray *stringChunks = [sourceString componentsSeparatedByString:@";ext="];
NSString *outString = [[stringChunks objectAtIndex:1] uppercaseString];

<强>更新

正如我在下面的评论中所述，这是一个蠢货。（如果在“ext =”之后有一个参数，它将失败）因此，这是使用NSURL的更强大的实现。（有点毫无意义，必须说。）我假设您的代码中原始URL中的空格字符是拼写错误，如果不是使用stringByReplacingOccurrencesOfString将其交换出来，如下所示。

// Create a URL based on a cleaned version of the input string.
NSString *sourceString = @"assets-library://asset/asset.MOV?id=100000009&amp;ext=MOV";
NSURL *sourceURL = [NSURL URLWithString:[sourceString stringByReplacingOccurrencesOfString:@"&amp;" withString:@"&"]];
NSArray *pathComponents = [[sourceURL query] componentsSeparatedByString:@"&"];

// Create a dictionary of the key/value portions of the query string.
NSMutableDictionary *queryParameters = [[NSMutableDictionary alloc] init];
for (NSString *component in pathComponents) {
[queryParameters setObject:[[component componentsSeparatedByString:@"="] objectAtIndex:1]
                    forKey:[[component componentsSeparatedByString:@"="] objectAtIndex:0]];
}

// Fetch the contents of the "ext" key and force to uppercase.
// We should really check that objectForKey doesn't return nil, but this is just
// an example.
NSString *outString = [[queryParameters objectForKey:@"ext"] uppercaseString];

[queryParameters release];

Answer 2

您可能需要查看NSURL，它明确支持解析URL字符串。

从字符串中获取值

2 个答案: