What constant can I use for the default Aqua space in Autolayout?

Question

According to the Cocoa Auto Layout Guide, I can use a dash in the visual constraint format language to \"denote the standard Aqua space:\"

[self addConstrain         


        

Answer 1

For iOS users:

#import "NSLayoutConstraint+StandardOffsets.h"

@implementation NSLayoutConstraint (StandardOffsets)

+ (CGFloat)standardConstantBetweenSiblings
{
    static CGFloat value;

    if(!isnormal(value)) {
        UIView *view = [UIView new] ;
        NSLayoutConstraint* constraintWithStandardConstantBetweenSiblings = [NSLayoutConstraint constraintsWithVisualFormat:@"[view]-[view]"  options:0  metrics:nil  views:NSDictionaryOfVariableBindings(view) ] [0] ;
        value = constraintWithStandardConstantBetweenSiblings.constant ;    // 8.0
    }
    return value;
}

+ (CGFloat)standardConstantBetweenSuperview
{
    static CGFloat value;

    if(!isnormal(value)) {
        UIView *view = [UIView new] ;
        UIView *superview = [UIView new] ;
        [superview addSubview:view] ;
        NSLayoutConstraint* constraintWithStandardConstantBetweenSuperview = [NSLayoutConstraint constraintsWithVisualFormat:@"[view]-|"  options:0  metrics:nil  views:NSDictionaryOfVariableBindings(view) ] [0] ;
        value = constraintWithStandardConstantBetweenSuperview.constant ;    // 20.0
    }
    return value;
}

@end

PS: I entered a bugreport that no constant is offered in the header files!