iOS 图片的按照比例拉伸

// 这是一个UIImage 的分类 （  UIImage+Extension.h   ）

UIImage+Extension.h

#import <UIKit/UIKit.h>

@interface UIImage (Extension)

+ (UIImage *)resizableImage:(NSString *)name;

@end

UIImage+Extension.m

#import "UIImage+Extension.h"

@implementation UIImage (Extension)

+ (UIImage *)resizableImage:(NSString *)name

{

UIImage *normal = [UIImage imageNamed:name];

CGFloat w = normal.size.width * 0.5;

CGFloat h = normal.size.height * 0.5;

return [normal resizableImageWithCapInsets:UIEdgeInsetsMake(h, w, h, w)];

}

@end

//  在其他地方使用时调用

[self.button setBackgroundImage:[UIImage resizableImage:@"chat_recive_nor"] forState:UIControlStateNormal];