I'm looking to be able to have the debugger break when it reaches a particular string match. As an example, I might have something like this:
Foo myObj = [self gimmeObj];
myObj might have a property called name. I want the debugger to stop on the assignment when
[myObj.name isEqualToString:@"Bar"];
How can I set my conditional breakpoint in Xcode to do that?
You can set a conditional break point in Xcode by setting the breakpoint normally, then control-click on it and select Edit Breakpoint (choose Run -> Show -> Breakpoints).
In the breakpoint entry, there is a Condition column.
Now, there are several issues to keep in mind for the condition. Firstly, gdb does not understand dot syntax, so instead of myObj.name, you must use [myObj name] (unless name is an ivar).
Next, as with most expressions in gdb, you must tell it the type of return result, namely "BOOL". So set a condition like:
(BOOL)[[myObj name] isEqualToString:@"Bar"]
Often it is actually easier to just do this in code by temporarily adding code like:
if ( [myObj.name isEqualToString:@"Bar"] ) {
NSLog( @"here" );
}
and then setting the break point on the NSLog. Then your condition can be arbitrarily complex without having to worry about what gdb can and can't parse.
I'm not sure if this will work, but you can try setting a breakpoint at that line of code, open up the debugger console (Cmd+Shift+R), and type
condition N (int)[[myObj name] isEqualToString:@"Bar"]
Where N is replaced by the number of the breakpoint (an integer).
If you mutate myObj.name using the setter, you can add a symbolic breakpoint on -[MyObjClass setName:] either from the Debugger Console or from the Run->Manage Breakpoints->Add Symbolic Breakpoint menu in Xcode. If not (why not? you probably shouldn't be modifying the instance variable directly except in the designated initializer or dealloc) you can set a watchpoint in gdb (use the Debugger Console in Xcode once the debugger is running). This page explains how. I don't believe Xcode exposes a UI for setting watchpoints without using the Debugger Console.