SnapKit/Snappy/LayoutConstraint.swift

//
//  Snappy
//
//  Copyright (c) 2011-2014 Masonry Team - https://github.com/Masonry
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.

#if os(iOS)
import UIKit
#else
import AppKit
#endif

/**
* LayoutConstraint is a subclass of NSLayoutConstraint to assist Snappy and also provide better debugging
*/
public class LayoutConstraint: NSLayoutConstraint {
    
    // internal
    
    internal var constraint: Constraint?
    
    internal class func layoutConstraintsInstalledOnView(view: View) -> Array<LayoutConstraint> {
        var constraints = objc_getAssociatedObject(view, &layoutConstraintsInstalledOnViewKey) as? Array<LayoutConstraint>
        if constraints != nil {
            return constraints!
        }
        return []
    }
    internal class func setLayoutConstraints(layoutConstraints: Array<LayoutConstraint>, installedOnView view: View) {
        objc_setAssociatedObject(view, &layoutConstraintsInstalledOnViewKey, layoutConstraints, UInt(OBJC_ASSOCIATION_RETAIN_NONATOMIC))
    }
}

private var layoutConstraintsInstalledOnViewKey = ""