iOS開發技巧

標籤：

UITableView的Group樣式下頂部空白處理

 

//分組列表頭部空白處理

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 0, 0.1)];

self.tableView.tableHeaderView = view;

 

擷取某個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;

}

 

兩種方法刪除NSUserDefaults所有記錄

 

//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];

}

 

列印系統所有登入的字型名稱

 

#pragma mark - 列印系統所有登入的字型名稱

void enumerateFonts()

{

for(NSString *familyName in [UIFont familyNames])

{

NSLog(@"%@",familyName);

NSArray *fontNames = [UIFont fontNamesForFamilyName:familyName];

for(NSString *fontName in fontNames)

{

NSLog(@"\t|- %@",fontName);

}

}

}

 

擷取圖片某一點的顏色

 

- (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;

}

 

字串反轉

 

第一種：

- (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;

}

//第二種：

- (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;

}

 

禁止鎖屏

 

預設情況下，當裝置一段時間沒有觸控動作時，iOS會鎖住螢幕。但有一些應用是不需要鎖屏的，比如視頻播放器。

 

[UIApplication sharedApplication].idleTimerDisabled = YES;

或

[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

 

模態推出透明介面

 

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調試不顯示記憶體佔用

 

editSCheme  裡面有個選項叫叫做enable zoombie Objects  取消選中

 

顯示隱藏檔案

 

//顯示

defaults write com.apple.finder AppleShowAllFiles -bool true

killall Finder

//隱藏

defaults write com.apple.finder AppleShowAllFiles -bool false

killall Finder

 

iOS跳轉到App Store下載應用評分

 

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

 

iOS 擷取漢字的拼音

 

+ (NSString *)transform:(NSString *)chinese

{

//將NSString裝換成NSMutableString

NSMutableString *pinyin = [chinese mutableCopy];

//將漢字轉換為拼音(帶音標)

CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformMandarinLatin, NO);

NSLog(@"%@", pinyin);

//去掉拼音的音標

CFStringTransform((__bridge CFMutableStringRef)pinyin, NULL, kCFStringTransformStripCombiningMarks, NO);

NSLog(@"%@", pinyin);

//返回最近結果

return pinyin;

}

 

手動更改iOS狀態列的顏色

 

- (void)setStatusBarBackgroundColor:(UIColor *)color

{

UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];

if ([statusBar respondsToSelector:@selector(setBackgroundColor:)])

{

statusBar.backgroundColor = color;

}

}

 

判斷當前ViewController是push還是present的方式顯示的

 

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];

}

 

擷取實際使用的LaunchImage圖片

 

- (NSString *)getLaunchImageName

{

CGSize viewSize = self.window.bounds.size;

// 豎屏

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在當前螢幕擷取第一響應

 

UIWindow * keyWindow = [[UIApplication sharedApplication] keyWindow];

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

 

判斷對象是否遵循了某協議

 

if ([self.selectedController conformsToProtocol:@protocol(RefreshPtotocol)])

{

[self.selectedController performSelector:@selector(onTriggerRefresh)];

}

 

判斷view是不是指定視圖的子視圖

 

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

 

NSArray 快速求總和 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的文字顏色

 

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

 

關於NSDateFormatter的格式

 

G: 公元時代，例如AD公元

yy: 年的後2位

yyyy: 完整年

MM: 月，顯示為1-12

MMM: 月，顯示為英文月份簡寫,如 Jan

MMMM: 月，顯示為英文月份全稱，如 Janualy

dd: 日，2位元表示，如02

d: 日，1-2位顯示，如 2

EEE: 簡寫星期幾，如Sun

EEEE: 全寫星期幾，如Sunday

aa: 上下午，AM/PM

H: 時，24小時制，0-23

K：時，12小時制，0-11

m: 分，1-2位

mm: 分，2位

s: 秒，1-2位

ss: 秒，2位

S: 毫秒

 

擷取一個類的所有子類

 

+ (NSArray *) allSubclasses

{

Class myClass = [self class];

NSMutableArray *mySubclasses = [NSMutableArray array];

unsigned int numOfClasses;

Class *classes = objc_copyClassList(&numOfClasses;);

for (unsigned int ci = 0; ci < numOfClasses; ci++)

{

Class superClass = classes[ci];

do{

superClass = class_getSuperclass(superClass);

} while (superClass && superClass != myClass);

if (superClass)

{

[mySubclasses addObject: classes[ci]];

}

}

free(classes);

return mySubclasses;

}

 

監測IOS裝置是否設定了代理，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(@"沒代理");

}

else

{

NSLog(@"設定了代理");

}

 

取消UICollectionView的隱式動畫

 

UICollectionView在reloadItems的時候，預設會附加一個隱式的fade動畫，有時候很討厭，尤其是當你的cell是複合cell的情況下(比如cell使用到了UIStackView)。

 

下面幾種方法都可以幫你去除這些動畫

 

//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];

}];

 

讓Xcode的控制台支援LLDB類型的列印

 

開啟終端輸入三條命令:

touch ~/.lldbinit

echo display @import UIKit >> ~/.lldbinit

echo target stop-hook add -o \"target stop-hook disable\" >> ~/.lldbinit

 

CocoaPods pod install/pod update更新慢的問題

 

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

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

如果不加後面的參數，預設會升級CocoaPods的spec倉庫，加一個參數可以省略這一步，然後速度就會提升不少

 

UIImage 佔用記憶體大小

 

UIImage *image = [UIImage imageNamed:@"aa"];

NSUInteger size  = CGImageGetHeight(image.CGImage) * CGImageGetBytesPerRow(image.CGImage);

 

GCD timer定時器

 

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); //每秒執行

dispatch_source_set_event_handler(timer, ^{

//@"倒計時結束，關閉"

dispatch_source_cancel(timer);

dispatch_async(dispatch_get_main_queue(), ^{

});

});

dispatch_resume(timer);

 

圖片上繪製文字 寫一個UIImage的category

 

- (UIImage *)imageWithTitle:(NSString *)title fontSize:(CGFloat)fontSize

{

//畫布大小

CGSize size=CGSizeMake(self.size.width,self.size.height);

//建立一個基於位元影像的上下文

UIGraphicsBeginImageContextWithOptions(size,NO,0.0);//opaque:NO  scale:0.0

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

//文字置中顯示在畫布上

NSMutableParagraphStyle* paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];

paragraphStyle.lineBreakMode = NSLineBreakByCharWrapping;

paragraphStyle.alignment=NSTextAlignmentCenter;//文字置中

//計算文字所佔的size,文字置中顯示在畫布上

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);

//繪製文字

[title drawInRect:rect withAttributes:@{ NSFontAttributeName:[UIFont systemFontOfSize:fontSize],NSForegroundColorAttributeName:[ UIColor whiteColor],NSParagraphStyleAttributeName:paragraphStyle}];

//返回繪製的新圖形

UIImage *newImage= UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return newImage;

}

 

尋找一個視圖的所有子視圖

 

- (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;

 }

iOS開發技巧