分享一些iOS开发实用的小技巧

1.设置navigationbar title颜色

 uicolor *whitecolor = [uicolor whitecolor];
nsdictionary *dic = [nsdictionary dictionarywithobject:whitecolor forkey:nsforegroundcolorattributename];
[self.navigationcontroller.navigationbar settitletextattributes:dic];

2.获取uicolor rgb

 uicolor *color = [uicolor colorwithred:0.0 green:0.0 blue:1.0 alpha:1.0];
const cgfloat *components = cgcolorgetcomponents(color.cgcolor);
nslog(@"red: %f", components[0]);
nslog(@"green: %f", components[1]);
nslog(@"blue: %f", components[2]);
nslog(@"alpha: %f", components[3]);

3.修改textfield的placeholder的字体颜色、大小

 [self.textfield setvalue:[uicolor redcolor] forkeypath:@"_placeholderlabel.textcolor"];
[self.textfield setvalue:[uifont boldsystemfontofsize:16] forkeypath:@"_placeholderlabel.font"];

4.将color转为uiimage

 - (uiimage *)createimagewithcolor:(uicolor *)color {
 cgrect rect = cgrectmake(0.0f, 0.0f, 1.0f, 1.0f);
 uigraphicsbeginimagecontext(rect.size);
 cgcontextref context = uigraphicsgetcurrentcontext();
 cgcontextsetfillcolorwithcolor(context, [color cgcolor]);
 cgcontextfillrect(context, rect);
 uiimage *theimage = uigraphicsgetimagefromcurrentimagecontext();
 uigraphicsendimagecontext();
 return theimage;
}

5.加载启动图的时候隐藏statusbar

在info.plist中加入status bar is initially hidden 设置为yes

6.获取按钮title的size

/**
 * 获取按钮title的size
 */
- (cgfloat)getbtntitlewidth:(uibutton*)btn {
 cgsize titlesize = [btn.titlelabel.text sizewithattributes:@{nsfontattributename:btn.titlelabel.font}];
 return titlesize;
}

7.设置status bar颜色

uiview *view = [[uiview alloc] initwithframe:cgrectmake(0, -20, screenwidth, 20)];[view setbackgroundcolor:color_app_main];
[viewcontroller.navigationcontroller.navigationbar addsubview:view];

8.json转dictionary，dictionary转json

+ (nsstring*)dictionarytojson:(nsdictionary *)dic {

 nserror *parseerror = nil;

 nsdata *jsondata = [nsjsonserialization datawithjsonobject:dic options:nsjsonwritingprettyprinted error:&parseerror];

 return [[nsstring alloc] initwithdata:jsondata encoding:nsutf8stringencoding];

}

+(nsdictionary *)jsontodic:(nsstring*)jsonstr {
  nsdata *jsondata = [jsonstr datausingencoding:nsutf8stringencoding];
  nserror *err;
  nsdictionary *dic = [nsjsonserialization jsonobjectwithdata:jsondata
               options:nsjsonreadingmutablecontainers
                error:&err];
  return dic;
}

9.是否允许推送

+(bool)isallowednotification{

 if ([[uidevice currentdevice].systemversion floatvalue] >= 8.0) {

  uiusernotificationsettings *setting = [[uiapplication sharedapplication] currentusernotificationsettings];

  if(uiusernotificationtypenone != setting.types) {

   return yes;
  }
 }
 nslog(@"不允许推送");
 return no;
}

10.磁盘空间相关

+ (nsstring *)memoryformatter:(long long)diskspace {
 nsstring *formatted;
 double bytes = 1.0 * diskspace;
 double megabytes = bytes / mb;
 double gigabytes = bytes / gb;
 if (gigabytes >= 1.0)
  formatted = [nsstring stringwithformat:@"%.2f gb", gigabytes];
 else if (megabytes >= 1.0)
  formatted = [nsstring stringwithformat:@"%.2f mb", megabytes];
 else
  formatted = [nsstring stringwithformat:@"%.2f bytes", bytes];
 nslog(@"fotmatted=%@",formatted);

 return formatted;
}

+ (nsstring *)totaldiskspace {

 long long space = [[[[nsfilemanager defaultmanager] attributesoffilesystemforpath:nshomedirectory() error:nil] objectforkey:nsfilesystemsize] longlongvalue];
 return [self memoryformatter:space];
}

+ (nsstring *)freediskspace {

 long long freespace = [[[[nsfilemanager defaultmanager] attributesoffilesystemforpath:nshomedirectory() error:nil] objectforkey:nsfilesystemfreesize] longlongvalue];
 return [self memoryformatter:freespace];
}

11.修改了leftbarbuttonitem如何恢复系统侧滑返回功能

 //设置代理
self.interactivepopgesturerecognizer.delegate = self;
#pragma mark - <uigesturerecognizerdelegate>
//实现代理方法:return yes :手势有效, no :手势无效
- (bool)gesturerecognizershouldbegin:(uigesturerecognizer *)gesturerecognizer
{
 //当导航控制器的子控制器个数 大于1 手势才有效
 return self.childviewcontrollers.count > 1;
}

或者用第三方 uinavigationcontroller+fdfullscreenpopgesture

12.使用uiappearance在某个状态下设置颜色,字体等不好使

只需要在对应的位置用layoutifneeded刷新一下就可以了

13.设置圆形图片

/** 设置圆形图片(放到分类中使用) */
- (uiimage *)cutcircleimage {
 uigraphicsbeginimagecontextwithoptions(self.size, no, 0.0);
 // 获取上下文
 cgcontextref ctr = uigraphicsgetcurrentcontext();
 // 设置圆形
 cgrect rect = cgrectmake(0, 0, self.size.width, self.size.height);
 cgcontextaddellipseinrect(ctr, rect);
 // 裁剪
 cgcontextclip(ctr);
 // 将图片画上去
 [self drawinrect:rect];
 uiimage *image = uigraphicsgetimagefromcurrentimagecontext();
 uigraphicsendimagecontext();
 return image;
}

14.如果在xib中有一个控件, 已经明确设置尺寸了,输出的frame也是对的, 但是显示出来的效果不一样(比如尺寸变大了), 如果是这种情况一般就是autoresizingmask自动伸缩属性在搞鬼!

解决办法如下:

//xib的awakefromnib方法中设置uiviewautoresizingnone进行清空

 - (void)awakefromnib {
 self.autoresizingmask = uiviewautoresizingnone;
}

15.通过图片data数据第一个字节 来获取图片扩展名

- (nsstring *)contenttypeforimagedata:(nsdata *)data {
 uint8_t c;
 [data getbytes:&c length:1];
 switch (c) {
  case 0xff:
   return @"jpeg";
  case 0x89:
   return @"png";  
  case 0x47:
   return @"gif";  
  case 0x49: 
  case 0x4d:
   return @"tiff";  
  case 0x52: 
   if ([data length] < 12) {
    return nil;
   }
   nsstring *teststring = [[nsstring alloc] initwithdata:[data subdatawithrange:nsmakerange(0, 12)] encoding:nsasciistringencoding];
   if ([teststring hasprefix:@"riff"] && [teststring hassuffix:@"webp"]) {
    return @"webp";
   }
   return nil;
 }
 return nil;
}

16.用0补全的方法

nsinteger count = 5;
//02代表:如果count不足2位 用0在最前面补全(2代表总输出的个数)
nsstring *string = [nsstring stringwithformat:@"%02zd",count];
//输出结果是: 05
nslog(@"%@", string);

总结

以上就是这篇文章的全部内容，希望本文中的这些小技巧能给大家开发ios的时候提供一定的帮助，如果有疑问大家可以留言交流。