NSURL总是零

Question

我有奇怪的问题而且能理解它

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];

NSString *mylink = [NSString stringWithFormat:@"%@/Bermad/IR_World/CaseStudy/%@",documentsPath,link];
NSURL *targetURL = [NSURL URLWithString:mylink];

NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
[WebView loadRequest:request];

链接已填充，我的链接也已填充，但targetURL为零，为什么？