iOS开发过程遇到的问题及解决方法

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Xcode代码提示功能消失

以前有代码提示，突然不提示可按照如下操作进行，首先打开命令行
1. cd ~/Library/Developer/Xcode/DerivedData
2. ls
3. 找到项目所用的目录（一般以项目名开头）
4. cd 项目目录名
5. rm -r Index 删除掉你的项目所用的索引文件夹

UITableView的Group样式下顶部空白处理

//分组列表头部空白处理
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 0, 0.1)];
self.tableView.tableHeaderView = view;

UITableView的plain样式下，取消区头停滞效果

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat sectionHeaderHeight = sectionHead.height;
    if (scrollView.contentOffset.y=0) {
        scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);
    }else if(scrollView.contentOffset.y>=sectionHeaderHeight) {
        scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight, 0, 0, 0);
    }
}

那个，其实，还是用Group样式吧哈哈。

获取某个view所在的控制器

- (UIViewController *)viewController {
  UIViewController *viewController = nil;  
  UIResponder *next = self.nextResponder;
  while (next) {
    if ([next isKindOfClass:[UIViewController class]]) {
      viewController = (UIViewController *)next;      
      break;    
    }    
    next = next.nextResponder;  
  } 
    return viewController;
}

两种方法删除NSUserDefaults所有记录

//方法一
NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier];
[[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];

//方法二
- (void)resetDefaults {
    NSUserDefaults * defs = [NSUserDefaults standardUserDefaults];
    NSDictionary * dict = [defs dictionaryRepresentation];
    for (id key in dict) {
        [defs removeObjectForKey:key];
    }
    [defs synchronize];
}

打印系统所有已注册的字体名称

//打印系统所有已注册的字体名称
void enumerateFonts() {
    for(NSString *familyName in [UIFont familyNames]) {
        NSLog(@"%@",familyName);               
        NSArray *fontNames = [UIFont fontNamesForFamilyName:familyName];       
        for(NSString *fontName in fontNames) {
            NSLog(@"\t|- %@",fontName);
       }
   }
}

获取图片某一点的颜色

- (UIColor*) getPixelColorAtLocation:(CGPoint)point inImage:(UIImage *)image {

    UIColor* color = nil;
    CGImageRef inImage = image.CGImage;
    CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];

    if (cgctx == NULL) {
        return nil; /* error */
    }
    size_t w = CGImageGetWidth(inImage);
    size_t h = CGImageGetHeight(inImage);
    CGRect rect = {{0,0},{w,h}};

    CGContextDrawImage(cgctx, rect, inImage);
    unsigned char* data = CGBitmapContextGetData (cgctx);
    if (data != NULL) {
        int offset = 4*((w*round(point.y))+round(point.x));
        int alpha =  data[offset];
        int red = data[offset+1];
        int green = data[offset+2];
        int blue = data[offset+3];
        color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:
                 (blue/255.0f) alpha:(alpha/255.0f)];
    }
    CGContextRelease(cgctx);
    if (data) {
        free(data);
    }
    return color;
}

字符串反转

//第一种：
- (NSString *)reverseWordsInString:(NSString *)str {    
    NSMutableString *newString = [[NSMutableString alloc] initWithCapacity:str.length];
    for (NSInteger i = str.length - 1; i >= 0 ; i --) {
        unichar ch = [str characterAtIndex:i];       
        [newString appendFormat:@"%c", ch];    
    }    
     return newString;
}

//第二种：
- (NSString*)reverseWordsInString:(NSString*)str {    
     NSMutableString *reverString = [NSMutableString stringWithCapacity:str.length];    
     [str enumerateSubstringsInRange:NSMakeRange(0, str.length) options:NSStringEnumerationReverse | NSStringEnumerationByComposedCharacterSequences  usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) { 
          [reverString appendString:substring];                         
      }];    
     return reverString;
}

禁止锁屏

//默认情况下，当设备一段时间没有触控动作时，iOS会锁住屏幕。但有一些应用是不需要锁屏的，比如视频播放器。

[UIApplication sharedApplication].idleTimerDisabled = YES;
//或
[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

模态推出透明界面

UIViewController *vc = [[UIViewController alloc] init];
UINavigationController *na = [[UINavigationController alloc] initWithRootViewController:vc];

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0) {
na.modalPresentationStyle = UIModalPresentationOverCurrentContext;
}else { self.modalPresentationStyle=UIModalPresentationCurrentContext;
}
[self presentViewController:na animated:YES completion:nil];

Xcode调试不显示内存占用

editSCheme 里面有个选项叫叫做enable zoombie Objects 取消选中

Mac显示隐藏文件

//显示
defaults write com.apple.finder AppleShowAllFiles -bool true
killall Finder

//隐藏
defaults write com.apple.finder AppleShowAllFiles -bool false
killall Finder

iOS跳转到App Store下载应用评分

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"itms-apps://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?type=Purple+Software&id=APPID"]];

iOS 获取汉字的拼音

+ (NSString *)transform:(NSString *)chinese {    
    //将NSString装换成NSMutableString 
    NSMutableString *pinyin = [chinese mutableCopy];    
    //将汉字转换为拼音(带音标)    
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformMandarinLatin, NO);    
    NSLog(@"%@", pinyin);    
    //去掉拼音的音标    
    CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformStripCombiningMarks, NO);    
    NSLog(@"%@", pinyin);    
    //返回最近结果    
    return pinyin;
}

手动更改iOS状态栏的颜色

- (void)setStatusBarBackgroundColor:(UIColor *)color
{
    UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];

    if ([statusBar respondsToSelector:@selector(setBackgroundColor:)])
    {
        statusBar.backgroundColor = color;    
    }
}

判断当前ViewController是push还是present的方式显示的

NSArray *viewcontrollers=self.navigationController.viewControllers;
if (viewcontrollers.count > 1) {
    if ([viewcontrollers objectAtIndex:viewcontrollers.count - 1] == self) {
        //push方式
       [self.navigationController popViewControllerAnimated:YES];
    }
}else {
    //present方式
    [self dismissViewControllerAnimated:YES completion:nil];
}

获取实际使用的LaunchImage图片

-

 (NSString *)getLaunchImageName {
    CGSize viewSize = self.window.bounds.size;
    // 竖屏    
    NSString *viewOrientation = @"Portrait";  
    NSString *launchImageName = nil;    
    NSArray* imagesDict = [[[NSBundle mainBundle] infoDictionary] valueForKey:@"UILaunchImages"];
    for (NSDictionary* dict in imagesDict) {
        CGSize imageSize = CGSizeFromString(dict[@"UILaunchImageSize"]);
        if (CGSizeEqualToSize(imageSize, viewSize) && [viewOrientation isEqualToString:dict[@"UILaunchImageOrientation"]]) {
            launchImageName = dict[@"UILaunchImageName"];        
        }    
    }    
    return launchImageName;
}

iOS在当前屏幕获取第一响应

UIWindow * keyWindow = [[UIApplication sharedApplication] keyWindow];
UIView * firstResponder = [keyWindow performSelector:@selector(firstResponder)];

判断对象是否遵循了某协议

if ([self.selectedController conformsToProtocol:@protocol(RefreshPtotocol)])
{
     [self.selectedController performSelector:@selector(onTriggerRefresh)];
}

判断view是不是指定视图的子视图

BOOL isView = [textView isDescendantOfView:self.view];

NSArray 快速求总和 最大值 最小值 和 平均值

NSArray *array = [NSArray arrayWithObjects:@"2.0", @"2.3", @"3.0", @"4.0", @"10", nil];
CGFloat sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];
CGFloat avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];
CGFloat max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];
CGFloat min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];
NSLog(@"%f\n%f\n%f\n%f",sum,avg,max,min);

修改UITextField中Placeholder的文字颜色

[textField setValue:[UIColor redColor] forKeyPath:@”_placeholderLabel.textColor”];

关于NSDateFormatter的格式

G: 公元时代，例如AD公元
yy: 年的后2位
yyyy: 完整年
MM: 月，显示为1-12
MMM: 月，显示为英文月份简写,如 Jan
MMMM: 月，显示为英文月份全称，如 Janualy
dd: 日，2位数表示，如02
d: 日，1-2位显示，如 2
EEE: 简写星期几，如Sun
EEEE: 全写星期几，如Sunday
aa: 上下午，AM/PM
H: 时，24小时制，0-23
K：时，12小时制，0-11
m: 分，1-2位
mm: 分，2位
s: 秒，1-2位
ss: 秒，2位
S: 毫秒

获取一个类的所有子类

+ (NSArray *) allSubclasses
{
    Class myClass = [self class];
    NSMutableArray *mySubclasses = [NSMutableArray array];
    unsigned int numOfClasses;
    Class *classes = objc_copyClassList(&numOfClasses;);
    for (unsigned int ci = 0; ci

监测IOS设备是否设置了代理，需要CFNetwork.framework

NSDictionary *proxySettings = (__bridge NSDictionary *)(CFNetworkCopySystemProxySettings());
NSArray *proxies = (__bridge NSArray *)(CFNetworkCopyProxiesForURL((__bridge CFURLRef _Nonnull)([NSURL URLWithString:@"http://www.baidu.com"]), (__bridge CFDictionaryRef _Nonnull)(proxySettings)));
NSLog(@"\n%@",proxies);

NSDictionary *settings = proxies[0];
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyHostNameKey]);
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyPortNumberKey]);
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyTypeKey]);
if ([[settings objectForKey:(NSString *)kCFProxyTypeKey] isEqualToString:@"kCFProxyTypeNone"]) {
     NSLog(@"没代理");
}else {
     NSLog(@"设置了代理");
}

阿拉伯数字转中文格式

+(NSString *)translation:(NSString *)arebic
{  
    NSString *str = arebic;
    NSArray *arabic_numerals = @[@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"0"];
    NSArray *chinese_numerals = @[@"一",@"二",@"三",@"四",@"五",@"六",@"七",@"八",@"九",@"零"];
    NSArray *digits = @[@"个",@"十",@"百",@"千",@"万",@"十",@"百",@"千",@"亿",@"十",@"百",@"千",@"兆"];
    NSDictionary *dictionary = [NSDictionary dictionaryWithObjects:chinese_numerals forKeys:arabic_numerals];

Base64编码与NSString对象或NSData对象的转换

// C

reate NSData object
NSData *nsdata = [@"iOS Developer Tips encoded in Base64"
  dataUsingEncoding:NSUTF8StringEncoding];

// Get NSString from NSData object in Base64
NSString *base64Encoded = [nsdata base64EncodedStringWithOptions:0];

// Print the Base64 encoded string
NSLog(@"Encoded: %@", base64Encoded);

// Let's go the other way...

// NSData from the Base64 encoded str
NSData *nsdataFromBase64String = [[NSData alloc]
  initWithBase64EncodedString:base64Encoded options:0];

// Decoded NSString from the NSData
NSString *base64Decoded = [[NSString alloc]
  initWithData:nsdataFromBase64String encoding:NSUTF8StringEncoding];
NSLog(@"Decoded: %@", base64Decoded);

取消UICollectionView的隐式动画

UICollectionView在reloadItems的时候，默认会附加一个隐式的fade动画，有时候很讨厌，尤其是当你的cell是复合cell的情况下(比如cell使用到了UIStackView)。
下面几种方法都可以帮你去除这些动画

//方法一
[UIView performWithoutAnimation:^{
    [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
}];

//方法二
[UIView animateWithDuration:0 animations:^{
    [collectionView performBatchUpdates:^{
        [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
    } completion:nil];
}];

//方法三
[UIView setAnimationsEnabled:NO];
[self.trackPanel performBatchUpdates:^{
    [collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
} completion:^(BOOL finished) {
    [UIView setAnimationsEnabled:YES];
}];

让Xcode的控制台支持LLDB类型的打印

打开终端输入三条命令:

touch ~/.lldbinit
echo display @import UIKit >> ~/.lldbinit
echo target stop-hook add -o \"target stop-hook disable\" >> ~/.lldbinit

CocoaPods pod install/pod update更新慢的问题

pod install --verbose --no-repo-update 
pod update --verbose --no-repo-update

如果不加后面的参数，默认会升级CocoaPods的spec仓库，加一个参数可以省略这一步，然后速度就会提升不少

UIImage 占用内存大小

UIImage *image = [UIImage imageNamed:@"aa"];
NSUInteger size  = CGImageGetHeight(image.CGImage) * CGImageGetBytesPerRow(image.CGImage);

GCD timer定时器

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue);
dispatch_source_set_timer(timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行
dispatch_source_set_event_handler(timer, ^{
    //@"倒计时结束，关闭"
    dispatch_source_cancel(timer); 
    dispatch_async(dispatch_get_main_queue(), ^{

    });
});
dispatch_resume(timer);

图片上绘制文字 写一个UIImage的category

- (UIImage *)imageWithTitle:(NSString *)title fontSize:(CGFloat)fontSize {
    //画布大小
    CGSize size=CGSizeMake(self.size.width,self.size.height);
    //创建一个基于位图的上下文
    UIGraphicsBeginImageContextWithOptions(size,NO,0.0);//opaque:NO  scale:0.0

    [self drawAtPoint:CGPointMake(0.0,0.0)];

    //文字居中显示在画布上
    NSMutableParagraphStyle* paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    paragraphStyle.lineBreakMode = NSLineBreakByCharWrapping;
    paragraphStyle.alignment=NSTextAlignmentCenter;//文字居中

    //计算文字所占的size,文字居中显示在画布上
    CGSize sizeText=[title boundingRectWithSize:self.size options:NSStringDrawingUsesLineFragmentOrigin
                                     attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}context:nil].size;
    CGFloat width = self.size.width;
    CGFloat height = self.size.height;

    CGRect rect = CGRectMake((width-sizeText.width)/2, (height-sizeText.height)/2, sizeText.width, sizeText.height);
    //绘制文字
    [title drawInRect:rect withAttributes:@{ NSFontAttributeName:[UIFont systemFontOfSize:fontSize],NSForegroundColorAttributeName:[ UIColor whiteColor],NSParagraphStyleAttributeName:paragraphStyle}];

    //返回绘制的新图形
    UIImage *newImage= UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

查找一个视图的所有子视图

- (NSMutableArray *)allSubViewsForView:(UIView *)view {
    NSMutableArray *array = [NSMutableArray arrayWithCapacity:0];
    for (UIView *subView in view.subviews) {
        [array addObject:subView];
        if (subView.subviews.count > 0) {
            [array addObjectsFromArray:[self allSubViewsForView:subView]];
        }
    }
    return array;
}

OC递归删除指定文件路径下的所有文件

+ (void)deleteFiles:(NSString *)path {
    //1.判断是文件还是目录
    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL isDir = NO;
    BOOL isExist = [manager fileExistsAtPath:path isDirectory:&isDir];
    if (isExist) {//路径存在
        //2.如果是目录
        if (isDir) {
            NSArray *allFiles = [manager contentsOfDirectoryAtPath:path error:nil];
            NSString *subPath = nil;
            for (NSString *subStr in allFiles) {
                subPath = [subPath stringByAppendingString:subStr];
                BOOL isSubDir = NO;
                [manager fileExistsAtPath:subPath isDirectory:&isSubDir];
                if (isSubDir) {//是目录
                    [self deleteFiles:subPath];
                }else {//是文件
                    [manager removeItemAtPath:subPath error:nil];
                }
            }
        }else {//是文件
            [manager removeItemAtPath:path error:nil];
        }
    }else {
        NSLog(@"您删除的文件或者目录不存在！！！");
    }
}