ios 开发常用小知识

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1.//计算文本长度

- (CGFloat)calculateTextNecessaryWidthWithString:(NSString *)string withFontSize:(CGFloat)size {

CGRect contentSize = [stringboundingRectWithSize:CGSizeMake(8000, size)options:NSStringDrawingUsesLineFragmentOriginattributes:@{NSFontAttributeName:[UIFontsystemFontOfSize:size]}context:nil];

return contentSize.size.width;

}

2.//计算文本高度

- (CGFloat)calculateTextNecessaryHightWithString:(NSString *)string withTextWidth:(CGFloat)width withFontSize:(CGFloat)size{

CGRect contentSize = [stringboundingRectWithSize:CGSizeMake(width,8000) options:NSStringDrawingUsesLineFragmentOriginattributes:@{NSFontAttributeName:[UIFontsystemFontOfSize:size]}context:nil];

return contentSize.size.height;

}

3./*! @brief

* 判断该字符串中是否存在指定的字符串（兼容iOS7）

* @param str 指定的字符串

* @return <#return value description#>

-(BOOL)extensionWithContainsString:(NSString *)strNS_AVAILABLE(10_10,7_0){

return __IPHONE_SYSTEM_VERSION <8 ? ([self rangeOfString:str].location != NSNotFound) : [self containsString:str];

}

4.//去除指定视图控制器的状态栏

在对应控制器里设置

-(BOOL)prefersStatusBarHidden{

return YES;

}

视然后还需在pilot文件里设置View controller-based status bar appearance 为YES。

5.设置定位提示语（允许应用内使用定位）

在plist中设置 NSLocationAlwaysUsageDescription 为YES

然后还需调用 requestWhenInUseAuthorization

6.检测手机系统版本 [[UIDevice currentDevice].systemVersion floatValue]

检测app本地版本 [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"]

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