iOS开发的几个小问题（二）

1. 图片压缩代码
   在图片上传过程中，照相机拍摄的图片太大，无法直接上传到服务器，需要先进行压缩。

/*1. pngData是用于上传的二进制流2. _imageToUpload是拍摄的照片文件，UIImage格式3. 0.3为float型，压缩大小4. kCompressionQuality不要调太低，会出现有时显示出黑图的异常情况 一般 0.3-0.7之间。 */float kCompressionQuality = 0.3；NSData *pngData = UIImageJPEGRepresentation(_imageToUpload, kCompressionQuality);

1. 代码实现边框线条的按钮

    UIButton *uploadButton = [[UIButton alloc]init];    uploadButton = [UIButton buttonWithType:UIButtonTypeCustom];    uploadButton.backgroundColor = [UIColor whiteColor];    CGRect buttonFrame = CGRectMake(20, 376 + 20, self.view.frame.size.width - 40, 30);    uploadButton.frame = buttonFrame;    [uploadButton.layer setMasksToBounds:YES];    uploadButton.layer.cornerRadius = 10;    uploadButton.layer.borderWidth = 1.0;    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGColorRef colorref = CGColorCreate(colorSpace,(CGFloat[]){ 0.0, 120.0/255.0, 1.0, 1.0 });    UIColor *systemBlue = [UIColor colorWithRed:0.0 green:120.0/255.0 blue:1.0 alpha:1.0];    uploadButton.layer.borderColor = colorref;    //uploadButton.backgroundColor = [UIColor whiteColor];    [uploadButton setTitle:@"确认上传" forState:UIControlStateNormal];    [uploadButton setTitleColor:systemBlue forState:UIControlStateNormal];    [uploadButton setTitleColor:[UIColor blackColor] forState:UIControlStateHighlighted];    [uploadButton addTarget:self action:@selector(didUpload) forControlEvents:UIControlEventTouchUpInside];    uploadButton.hidden = YES;    [self.view addSubview:uploadButton];

效果图：

1. 分享一个好用的查询快递的连接： 快递查询