Question

why can this code not access ‘borderWidth’ (iphone code attached)

This is based on a simple test project, but I did add QuartzCore framework however this didn’t help. Still is throwing the error, see code below. Another project where I do this it works fine and I can’t see the difference

#import "Customview.h"
@implementation Customview
- (id)initWithCoder:(NSCoder *)coder {
    self = [super initWithCoder:coder];
    if (self) {

        // UI Layout
        self.layer.borderWidth = 5; // ERROR error: accessing unknown 'borderWidth' component of a property
    }
    return self;
}

Answer 1

You need to add QuartzCore framework in order to access layer property of any UIView. Did you add that ?

Add Framework from following steps if you are using xCode 4

1. Select Target
2. Build Phases
3. Link Binary with Library Section
4. Tap + and find for the Quartz
5. Add Framework. 

Now, Import it where ever you want to access layer property of any UIControl.

#import <QuartzCore/QuartzCore.h>

Hope this help.