返回强制转换为ARC下CFStringRef的NSString * —如何摆脱分析器警告？

Question

Here is my function:

CFStringRef nameWithType (someEnum type) {
  NSString* r;
  switch (type) {
    case type1:
      r=@"type1";
      break;
    case type2:
      r=@"type2";
      break;
    case type3:
      r=@"type3";
      break;
  }
  return (__bridge CFStringRef)r;  // analyzer warns: Address of stack memory associated with local variable 'r' returned to caller.
}

Answer 1

This will get rid of the very hard to eliminate analyzer warning.

CFStringRef nameWithType2(someEnum type){
    CFStringRef string = NULL;
    switch (type) {
        case type1:
            string = (__bridge CFStringRef)@"type1";
            break;
        case type2:
            string = (__bridge CFStringRef)@"type2";
            break;
        case type3:
            string = (__bridge CFStringRef)@"type3";
            break;
    }
    return string;
}

Just remember to not let this memory leak.

Answer 2

Actually there is the "traditional way" (from the time before there was NSObject) to not not use NSString literals, but instead work with the CFSTR macro like so:

CFStringRef nameWithType2(someEnum type){
    CFStringRef string = NULL;
    switch (type) {
        case type1:
            string = CFSTR("type1");
            break;
        case type2:
            string = CFSTR("type2");
            break;
        case type3:
            string = CFSTR("type3");
            break;
    }
    return string;
}

CFSTR(c_string) is the shortest method to create a CFStringRef and much shorter than (__bridge CFStringRef)@"NSString"

Also if somebody sees this code you get higher geek cred for knowing CFSTR. It smells of N00B to create an NSString literal, then convert that into a CFStringRef AND needing to add ARC memory management ownership transferance tags.... versus creating a CFStringRef right away.