Programming iOS 6, 3rd Edition

Static Analyzer

From time to time, you should use the static analyzer to look for possible sources of error in your code; choose Product → Analyze (Shift-Command-B). This command causes your code to be compiled, and the static analyzer studies it and reports its findings in the Issue navigator and in your code.

The static analyzer is static (it’s analyzing your code, not debugging in real time), but it is remarkably intelligent and may well alert you to potential problems that could otherwise escape your notice. You might think that the compiler — including ARC, if you’re using it — knows all there is to know about your code; and it is certainly true that one of the main reasons for using the static analyzer, namely, to assist with manual memory management of Objective-C instances, is essentially gone if you’re using ARC. Still, the static analyzer actually studies the possible values and paths of execution in your code, and can detect potential sources of trouble in your program’s logic that no mere compiler would worry about. For example, in this code, the static analyzer knows that i in the second line is uninitialized:

int i;
if (i) NSLog(@"here");

In this code, the static analyzer knows that the second line throws away the existing value of i without that value ever having been read:

int i=0;
i=1;

Those are tiny problems, but they illustrate how, in a complex program, the static analyzer is capable of noticing possible sources of trouble and bringing them to your attention. For ...