Objective-c Try/Catch not catching

问题

Is there a reason why the following wouldn't work?

@try {
    CFGetTypeID( NULL );
}
@catch (NSException * e) {
    NSLog(@"Exception: %@", e);
}
@finally {
    NSLog(@"finally");
}

Similar to the try/catch question, only it seems the above block crashes everytime. I know my debugger is setup correctly, as I setup a try/catch above from the other question:

// Test working try catch
NSString* test = [NSString stringWithString:@"ss"];

@try {
    [test characterAtIndex:6];
}
@catch (NSException * e) {
    NSLog(@"Exception: %@", e);
}
@finally {
    NSLog(@"finally");
}

// Now test NULL entry
@try {
    CFGetTypeID( NULL );
}
@catch (NSException * e) {
    NSLog(@"Exception: %@", e);
}
@finally {
    NSLog(@"finally");
}

回答1:

Yes, there is a very simple reason. Namely, CFGetTypeID(NULL) isn't throwing an exception. It's crashing. You can't catch crashes like this.

来源：https://stackoverflow.com/questions/9745581/objective-c-try-catch-not-catching