swift开发笔记21

let frame = CGRect(x: xOffset[column], y: yOffset[column], columnWidth, height: height)

let insetFrame = frame.insetBy(dx: cellPadding, dy: cellPadding)

attributes.frame.intersects(rect)

ceil(rect.height)

Variable 'photos' passed by reference before being initialized

var photos: [Photo]

if let photo = photo

Class 'AnnotatedPhotoCell' has no initializers

Initializer for conditional binding must have Optional type,

// 类方法

class func allPhotos() -> [Photo] {}

if let patternImage = UIImage.init(named: "Pattern") {
　　view.backgroundColor = UIColor.init(patternImage: patternImage)
}

// model刷新UI；
var photo: Photo? {
didSet{
if let photo = photo {
imageView.image = photo.image
captionLable.text = photo.caption
commentLabel.text = photo.comment
}
}
}

DESIGNATED，CONVENIENCE 和 REQUIRED

 http://swifter.tips/init-keywords/