Answer 1

Answer 2

尝试在主线程上运行连接：

NSURLConnection * connection = [[NSURLConnection alloc] initWithRequest:request
                                         delegate:self startImmediately:NO];

[connection scheduleInRunLoop:[NSRunLoop mainRunLoop] 
            forMode:NSDefaultRunLoopMode];
[connection start];

Answer 3

Answer 4

Answer 5

我认为您的类头文件中可能遗漏了NSURLConnectionDelegate。

例如：

@interface yourClass : NSObject <NSURLConnectionDelegate>