http://stackoverflow.com/questions/2658738/the-simplest-way-to-resize-an-uiimage
http://stackoverflow.com/questions/185652/how-to-scale-a-uiimageview-proportionally
http://www.samwirch.com/blog/cropping-and-resizing-images-camera-ios-and-objective-c
http://stackoverflow.com/questions/12579876/how-to-quickly-estimate-file-sizes-of-resized-images-on-ios
http://blog.csdn.net/lovenjoe/article/details/7484217
http://blog.sina.com.cn/s/blog_721e233d010197a5.html
http://stackoverflow.com/questions/8701751/uiimageview-change-size-to-image-size
http://stackoverflow.com/questions/6385324/how-to-get-size-of-uiimage-in-bytes-in-ios-4-0
http://stackoverflow.com/questions/9506871/image-compression-by-size-iphone-sdk
http://stackoverflow.com/questions/15054016/nsdata-length-of-an-image-compressed-with-uiimagejpegrepresentation
iOS resize image