iOS基础开发技巧二

这里主要讲一些我在日常开发中用到的一些小的技巧,其实也算不上技巧吧,就是省去一些不必要的代码,或者有的小问题困扰你很久说不行在这里你能找到答案

打印系统所有已注册的字体名称

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- (void)enumerateFonts{
for(NSString *familyName in [UIFont familyNames])
{
NSLog(@"%@",familyName);
NSArray *fontNames = [UIFont fontNamesForFamilyName:familyName];
for(NSString *fontName in fontNames)
{
NSLog(@"\t|- %@",fontName);
}
}
}

字符串反转

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- (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

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[UIApplication sharedApplication].idleTimerDisabled = YES;

字符串按多个符号分割

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- (void)seprartStringWithCharters{
NSString *str = @"abc,dsd/123.789";
NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@",/."];
NSLog(@"%@",[str componentsSeparatedByCharactersInSet:set]);
}

iOS跳转到App Store下载应用评分

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

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

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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

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- (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

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

判断对象是否遵循了某协议

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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

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

NSArray 快速求总和 最大值 最小值 和 平均值

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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

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

关于NSDateFormatter的格式

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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

阿拉伯数字转中文格式

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+(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];

NSMutableArray *sums = [NSMutableArray array];
for (int i = 0; i < str.length; i ++) {
NSString *substr = [str substringWithRange:NSMakeRange(i, 1)];
NSString *a = [dictionary objectForKey:substr];
NSString *b = digits[str.length -i-1];
NSString *sum = [a stringByAppendingString:b];
if ([a isEqualToString:chinese_numerals[9]])
{
if([b isEqualToString:digits[4]] || [b isEqualToString:digits[8]])
{
sum = b;
if ([[sums lastObject] isEqualToString:chinese_numerals[9]])
{
[sums removeLastObject];
}
}else
{
sum = chinese_numerals[9];
}

if ([[sums lastObject] isEqualToString:sum])
{
continue;
}
}

[sums addObject:sum];
}

NSString *sumStr = [sums componentsJoinedByString:@""];
NSString *chinese = [sumStr substringToIndex:sumStr.length-1];
NSLog(@"%@",str);
NSLog(@"%@",chinese);
return chinese;
}

Base64编码与NSString对象或NSData对象的转换

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


NSString *base64Encoded = [nsdata base64EncodedStringWithOptions:0];


NSLog(@"Encoded: %@", base64Encoded);

//另外一种方法


NSData *nsdataFromBase64String = [[NSData alloc]
initWithBase64EncodedString:base64Encoded options:0];


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

取消UICollectionView的隐式动画

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//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];
}];

查看某个UIImage占用内存大小

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

UIView设置部分圆角

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CGRect rect = view.bounds;
CGSize radio = CGSizeMake(30, 30);//圆角尺寸
UIRectCorner corner = UIRectCornerTopLeft|UIRectCornerTopRight;//这只圆角位置
UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:corner cornerRadii:radio];
CAShapeLayer *masklayer = [[CAShapeLayer alloc]init];//创建shapelayer
masklayer.frame = view.bounds;
masklayer.path = path.CGPath;//设置路径
view.layer.mask = masklayer;

去掉导航栏的back标题

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[[UIBarButtonItemappearance]setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)forBarMetrics:UIBarMetricsDefault];

dispatch_group的使用

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dispatch_group_t dispatchGroup = dispatch_group_create();
dispatch_group_enter(dispatchGroup);
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
NSLog(@"第一个请求完成");
dispatch_group_leave(dispatchGroup);
});

dispatch_group_enter(dispatchGroup);

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(10 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
NSLog(@"第二个请求完成");
dispatch_group_leave(dispatchGroup);
});

dispatch_group_notify(dispatchGroup, dispatch_get_main_queue(), ^(){
NSLog(@"请求完成");
});

获取私有属性和成员变量 记得引入runtime

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//获取私有属性 比如设置UIDatePicker的字体颜色
- (void)setTextColor
{
//获取所有的属性,去查看有没有对应的属性
unsigned int count = 0;
objc_property_t *propertys = class_copyPropertyList([UIDatePicker class], &count);
for(int i = 0;i < count;i ++)
{
//获得每一个属性
objc_property_t property = propertys[i];
//获得属性对应的nsstring
NSString *propertyName = [NSString stringWithCString:property_getName(property) encoding:NSUTF8StringEncoding];
//输出打印看对应的属性
NSLog(@"propertyname = %@",propertyName);
if ([propertyName isEqualToString:@"textColor"])
{
[datePicker setValue:[UIColor whiteColor] forKey:propertyName];
}
}
}

//获得成员变量 比如修改UIAlertAction的按钮字体颜色
unsigned int count = 0;
Ivar *ivars = class_copyIvarList([UIAlertAction class], &count);
for(int i =0;i < count;i ++)
{
Ivar ivar = ivars[i];
NSString *ivarName = [NSString stringWithCString:ivar_getName(ivar) encoding:NSUTF8StringEncoding];
NSLog(@"uialertion.ivarName = %@",ivarName);
if ([ivarName isEqualToString:@"_titleTextColor"])
{
[alertOk setValue:[UIColor blueColor] forKey:@"titleTextColor"];
[alertCancel setValue:[UIColor purpleColor] forKey:@"titleTextColor"];
}
}

iOS中数字的格式化

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//通过NSNumberFormatter,同样可以设置NSNumber输出的格式。例如如下代码:
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
formatter.numberStyle = NSNumberFormatterDecimalStyle;
NSString *string = [formatter stringFromNumber:[NSNumber numberWithInt:123456789]];
NSLog(@"Formatted number string:%@",string);
//输出结果为:[1223:403] Formatted number string:123,456,789

//其中NSNumberFormatter类有个属性numberStyle,它是一个枚举型,设置不同的值可以输出不同的数字格式。该枚举包括:
typedef NS_ENUM(NSUInteger, NSNumberFormatterStyle) {
NSNumberFormatterNoStyle = kCFNumberFormatterNoStyle,
NSNumberFormatterDecimalStyle = kCFNumberFormatterDecimalStyle,
NSNumberFormatterCurrencyStyle = kCFNumberFormatterCurrencyStyle,
NSNumberFormatterPercentStyle = kCFNumberFormatterPercentStyle,
NSNumberFormatterScientificStyle = kCFNumberFormatterScientificStyle,
NSNumberFormatterSpellOutStyle = kCFNumberFormatterSpellOutStyle
};
//各个枚举对应输出数字格式的效果如下:其中第三项和最后一项的输出会根据系统设置的语言区域的不同而不同。
[1243:403] Formatted number string:123456789
[1243:403] Formatted number string:123,456,789
[1243:403] Formatted number string:¥123,456,789.00
[1243:403] Formatted number string:-539,222,988%
[1243:403] Formatted number string:1.23456789E8
[1243:403] Formatted number string:一亿二千三百四十五万六千七百八十九

获取WebView所有的图片地址

在网页加载完成时,通过js获取图片和添加点击的识别方式

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//UIWebView
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
//这里是js,主要目的实现对url的获取
static NSString * const jsGetImages =
@"function getImages(){\
var objs = document.getElementsByTagName(\"img\");\
var imgScr = '';\
for(var i=0;i<objs.length;i++){\
imgScr = imgScr + objs[i].src + '+';\
};\
return imgScr;\
};";

[webView stringByEvaluatingJavaScriptFromString:jsGetImages];//注入js方法
NSString *urlResult = [webView stringByEvaluatingJavaScriptFromString:@"getImages()"];
NSArray *urlArray = [NSMutableArray arrayWithArray:[urlResult componentsSeparatedByString:@"+"]];
//urlResurlt 就是获取到得所有图片的url的拼接;mUrlArray就是所有Url的数组
}

//WKWebView
- (void)webView:(WKWebView *)webView didFinishNavigation:(null_unspecified WKNavigation *)navigation
{
static NSString * const jsGetImages =
@"function getImages(){\
var objs = document.getElementsByTagName(\"img\");\
var imgScr = '';\
for(var i=0;i<objs.length;i++){\
imgScr = imgScr + objs[i].src + '+';\
};\
return imgScr;\
};";

[webView evaluateJavaScript:jsGetImages completionHandler:nil];
[webView evaluateJavaScript:@"getImages()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
NSLog(@"%@",result);
}];
}

获取到webview的高度

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CGFloat height = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];