IOS开发基础知识–碎片8

1:用UIImageView作为背景，但直接把按钮或者UITextField放在上面无法相应事件。

解决办法：UIImageView默认的UserInteractionEnabled是NO，把它修改成YES,或者可以直接在XCODE上面的view有个属性勾选User Interaction Enabled遇到的场景(在滚动视图里面放一个图片视图，在图片视图上又放置一个按键，发现一直没有响应效果);

2:AFnetWorking报”Request failed: unacceptable content-type: text/html”

对应到自己的项目里面，我用的是AFNetworking这套网络请求包，需要改的是：AFURLResponseSerialization.m文件223行：self.acceptableContentTypes = [NSSetsetWithObjects:@"application/json", @"text/html",@"text/json",@"text/javascript", nil];加上@"text/html",部分，其实就是添加一种服务器返回的数据格式。

3:NSMutableArray和NSArray的相互转换

// NSArray --> NSMutableArray
NSMutableArray *myMutableArray = [myArray mutableCopy];  // NSMutableArray --> NSArray
NSArray *myArray = [myMutableArray copy];  

4:自定义系统导航条上面的返回按钮，以及文字，右侧收藏按钮

 //中间标题
   UILabel *navLabel = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
   navLabel.text = @"团购详情";
   navLabel.textColor = [UIColor whiteColor];
   navLabel.font = [UIFont systemFontOfSize:];
   navLabel.textAlignment = NSTextAlignmentCenter;
   self.navigationItem.titleView = navLabel;   //右边收藏按钮
   UIButton *rightButton = [UIButton buttonWithType:UIButtonTypeCustom];
   rightButton.frame = CGRectMake(, , , );
   [rightButton setBackgroundImage:LOAD_IMAGE(@"meishoucang") forState:UIControlStateNormal];
   [rightButton addTarget:self action:@selector(doShouCang) forControlEvents:UIControlEventTouchUpInside];
   UIBarButtonItem *rightItem = [[UIBarButtonItem alloc] initWithCustomView:rightButton];
   self.navigationItem.rightBarButtonItem = rightItem;   //左边返回按钮
   UIButton *fanHuiButton = [UIButton buttonWithType:UIButtonTypeCustom];
   fanHuiButton.frame = CGRectMake(, , , );
   [fanHuiButton setBackgroundImage:LOAD_IMAGE(@"fanhuijiantou") forState:UIControlStateNormal];
   [fanHuiButton addTarget:self action:@selector(doFanHui) forControlEvents:UIControlEventTouchUpInside];
   UIBarButtonItem *leftItem = [[UIBarButtonItem alloc] initWithCustomView:fanHuiButton];
   self.navigationItem.leftBarButtonItem = leftItem;导航条上的title字体， 字号 可以这么定义，完全使用系统的
[self.navigationController.navigationBar setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:
       [UIColor colorWithRed:1.0/ green:1.0/ blue:1.0/ alpha:], UITextAttributeTextColor,[UIColor clearColor],UITextAttributeTextShadowColor,[UIFont systemFontOfSize:],UITextAttributeFont,nil]];

5:清理UITableView底部空的列

self.tableView.tableFooterView = [[UIView alloc] init];

6:如何隐藏navigation跳转后的头部右键

//隐藏头部左边的返回
self.navigationItem.hidesBackButton=YES;
//隐藏头部右边
self.navigationItem.rightBarButtonItem.customView.hidden=YES;

7:如要给UICollectionViewController视图设置背景图

UIImage *image=[UIImage imageNamed:@"AppBg"];
self.collectionView.layer.contents=(id)image.CGImage;

8:可以在其它地方修改rootViewController

UIWindow *window = [UIApplication sharedApplication].keyWindow;
    window.rootViewController = [[HVWTabBarViewController alloc] init];

9:新浪微博授权登录报Warning: Attempt to present on whose view is not in the window hierarchy!

 IntroductoryViewController *introductory=[mainStoryboard instantiateViewControllerWithIdentifier:@"introductoryview"];
        UINavigationController *rootNavigationController=[[UINavigationController alloc] initWithRootViewController:introductory];
            self.window.rootViewController=rootNavigationController;主要问题是a跳转到b,然后b放一个授权新浪微博的按键，增加一个UINavigationController，然后在a跳转到b时用nav跳转：    UIStoryboard *mainStoryboard=[UIStoryboard storyboardWithName:@"Main" bundle:nil];
    LoginViewController* loginviewControll=[mainStoryboard instantiateViewControllerWithIdentifier:@"loginviewcontroller"];
    [self.navigationController pushViewController:loginviewControll  animated:YES];

10:在引入第三方TcweiboSDK报linker command failed with exit code1(use -v to see invocation)

是因为重复引入libTCWeiboSDK这个类库，TARGETS-PROJECT-Build Phases-Link Binary With Libraries中，有三个libTcweiboSDK,可以删除libTCWeiboSDK-I386.a

11:NSUserDefaults存放民NSDictionary

注意：NSUserDefaults支持的数据类型有NSString、 NSNumber、NSDate、 NSArray、NSDictionary、BOOL、NSInteger、NSFloat等系统定义的数据类型。
本次遇到的问题：当NSDictionary里面的值为null时，要写入NSUserDefaults会报异常（attempt to insert non-property list object）；
解决方式：把字典中的值进行过滤处理，为空的转化成字符串的空值；代码如下(创建一个扩展类):@implementation NSDictionary(Common)
-(NSDictionary *) changeDictionaryNotNill
{
    NSMutableDictionary *muResult=[[NSMutableDictionary alloc]init];
    NSEnumerator *enumerator=[self keyEnumerator];
    id key;
    while ((key=[enumerator nextObject])) {
        id value=[self objectForKey:key];
        if ((NSNull *)value==[NSNull null]) {
            [muResult setObject:@"" forKey:key];
        }
        else
        {
            [muResult setObject:value forKey:key];
        }
    }
    return muResult;
}
@end