首先謝謝各位大神的分享，小兵在這里整理收集iOS 開發中各種小技巧，有喜歡的可以關注下；
感謝 判若兩人丶
UITextField使用注意
先貼一個UITextField如何設置占位文字的顏色, 如果不先設置占位文字, 占位文字的顏色是不管用的:
//先設置占位文字
textField.placeholder = @"設置了占位文字內容以后, 才能設置占位文字的顏色";
//占位文字顏色
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
大家監聽UITextField文字的改變會用到代理:
#pragma mark - <UITextFieldDelegate>
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
//這里監聽文字改變
return YES;
}
但是這個代理方法監聽會有問題如下圖:
2353624-366e3c826e58adaf.png
2353624-44c4588449a266b4.png
所以我們要監聽UITextField的文字改變不建議使用代理, 我們用addTarget監聽文字
[textField addTarget:self action:@selector(textEditingChanged) forControlEvents:UIControlEventEditingChanged];
TableView拉伸頭部圖片、導航欄漸變效果
self.tableView.contentInset = UIEdgeInsetsMake(headH + tabBarH, 0, 0, 0);
self.automaticallyAdjustsScrollViewInsets = NO;
// 給導航條的背景圖片傳遞一個空圖片的UIImage對象
[self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
// 隱藏底部陰影條，傳遞一個空圖片的UIImage對象
[self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init]];
//設置圖片透明度
- (UIImage *)imageByApplyingAlpha:(CGFloat)alpha image:(UIImage*)image {
UIGraphicsBeginImageContextWithOptions(image.size, NO, 0.0f);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGRect area = CGRectMake(0, 0, image.size.width, image.size.height);
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -area.size.height);
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
CGContextSetAlpha(ctx, alpha);
CGContextDrawImage(ctx, area, image.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
- (UIImage *)imageWithColor:(UIColor *)color {
// 描述矩形
CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
// 開啟位圖上下文
UIGraphicsBeginImageContext(rect.size);
// 獲取位圖上下文
CGContextRef context = UIGraphicsGetCurrentContext();
// 使用color演示填充上下文
CGContextSetFillColorWithColor(context, [color CGColor]);
// 渲染上下文
CGContextFillRect(context, rect);
// 從上下文中獲取圖片
UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
// 結束上下文
UIGraphicsEndImageContext();
return theImage;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGFloat offsetY = scrollView.contentOffset.y;
CGFloat delta = offsetY - _lastOffsetY;
// 往上拖動，高度減少。
CGFloat height = headH - delta;
if (height < headMinH) {
height = headMinH;
}
_headHCons.constant = height;
// 設置導航條的背景圖片
CGFloat alpha = delta / (headH - headMinH);
// 當alpha大于1，導航條半透明，因此做處理，大于1，就直接=0.99
if (alpha >= 1) {
alpha = 0.99;
}
_nameLabel.alpha = alpha;
// 設置導航條的背景圖片
UIImage *image = [UIImage imageWithColor:[UIColor colorWithWhite:1 alpha:alpha]];
[self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
}
獲取通訊錄（聯系人信息）
Unknown.png
Unknown-1.png
磁盤總空間大小
1、 獲取磁盤總空間大小
//磁盤總空間
+ (CGFloat)diskOfAllSizeMBytes{
CGFloat size = 0.0;
NSError *error;
NSDictionary *dic = [[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:&error];
if (error) {
#ifdef DEBUG
NSLog(@"error: %@", error.localizedDescription);
#endif
}else{
NSNumber *number = [dic objectForKey:NSFileSystemSize];
size = [number floatValue]/1024/1024;
}
return size;
}
2、 獲取磁盤可用空間大小
//磁盤可用空間
+ (CGFloat)diskOfFreeSizeMBytes{
CGFloat size = 0.0;
NSError *error;
NSDictionary *dic = [[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:&error];
if (error) {
#ifdef DEBUG
NSLog(@"error: %@", error.localizedDescription);
#endif
}else{
NSNumber *number = [dic objectForKey:NSFileSystemFreeSize];
size = [number floatValue]/1024/1024;
}
return size;
}
3、 獲取指定路徑下某個文件的大小
//獲取文件大小
+ (long long)fileSizeAtPath:(NSString *)filePath{
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:filePath]) return 0;
return [[fileManager attributesOfItemAtPath:filePath error:nil] fileSize];
}
4、獲取文件夾下所有文件的大小
//獲取文件夾下所有文件的大小
+ (long long)folderSizeAtPath:(NSString *)folderPath{
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:folderPath]) return 0;
NSEnumerator *filesEnumerator = [[fileManager subpathsAtPath:folderPath] objectEnumerator];
NSString *fileName;
long long folerSize = 0;
while ((fileName = [filesEnumerator nextObject]) != nil) {
NSString *filePath = [folderPath stringByAppendingPathComponent:fileName];
folerSize += [self fileSizeAtPath:filePath];
}
return folerSize;
}
NSString處理
1、 獲取字符串(或漢字)首字母
//獲取字符串(或漢字)首字母
+ (NSString *)firstCharacterWithString:(NSString *)string{
NSMutableString *str = [NSMutableString stringWithString:string];
CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformMandarinLatin, NO);
CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformStripDiacritics, NO);
NSString *pingyin = [str capitalizedString];
return [pingyin substringToIndex:1];
}
2、將字符串數組按照元素首字母順序進行排序分組
//將字符串數組按照元素首字母順序進行排序分組
-(NSDictionary *)dictionaryOrderByCharacterWithOriginalArray:(NSArray *)array{
if (array.count == 0) {
return nil;
}
for (id obj in array) {
if (![obj isKindOfClass:[NSString class]]) {
return nil;
}
}
UILocalizedIndexedCollation *indexedCollation = [UILocalizedIndexedCollation currentCollation];
NSMutableArray *objects = [NSMutableArray arrayWithCapacity:indexedCollation.sectionTitles.count];
//創建27個分組數組
for (int i = 0; i < indexedCollation.sectionTitles.count; i++) {
NSMutableArray *obj = [NSMutableArray array];
[objects addObject:obj];
}
NSMutableArray *keys = [NSMutableArray arrayWithCapacity:objects.count];
//按字母順序進行分組
NSInteger lastIndex = -1;
for (int i = 0; i < array.count; i++) {
NSInteger index = [indexedCollation sectionForObject:array[i] collationStringSelector:@selector(uppercaseString)];
[[objects objectAtIndex:index] addObject:array[i]];
lastIndex = index;
}
//去掉空數組
for (int i = 0; i < objects.count; i++) {
NSMutableArray *obj = objects[i];
if (obj.count == 0) {
[objects removeObject:obj];
}
}
//獲取索引字母
for (NSMutableArray *obj in objects) {
NSString *str = obj[0];
NSString *key = [self firstCharacterWithString:str];
[keys addObject:key];
}
NSMutableDictionary *dic = [NSMutableDictionary dictionary];
[dic setObject:objects forKey:keys];
return dic;
}
//獲取字符串(或漢字)首字母
- (NSString *)firstCharacterWithString:(NSString *)string{
NSMutableString *str = [NSMutableString stringWithString:string];
CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformMandarinLatin, NO);
CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformStripDiacritics, NO);
NSString *pingyin = [str capitalizedString];
return [pingyin substringToIndex:1];
}
NSArray *arr = @[@"guangzhou", @"shanghai", @"北京", @"henan", @"hainan"];
NSDictionary *dic = [Utilities dictionaryOrderByCharacterWithOriginalArray:arr];
NSLog(@"\n\ndic: %@", dic);
輸出結果如下:
Unknown-2.png
UIImage 相關處理
1、對圖片進行濾鏡處理
#pragma mark - 對圖片進行濾鏡處理
// 懷舊 --> CIPhotoEffectInstant 單色 --> CIPhotoEffectMono
// 黑白 --> CIPhotoEffectNoir 褪色 --> CIPhotoEffectFade
// 色調 --> CIPhotoEffectTonal 沖印 --> CIPhotoEffectProcess
// 歲月 --> CIPhotoEffectTransfer 鉻黃 --> CIPhotoEffectChrome
// CILinearToSRGBToneCurve, CISRGBToneCurveToLinear, CIGaussianBlur, CIBoxBlur, CIDiscBlur, CISepiaTone, CIDepthOfField
+ (UIImage *)filterWithOriginalImage:(UIImage *)image filterName:(NSString *)name{
CIContext *context = [CIContext contextWithOptions:nil];
CIImage *inputImage = [[CIImage alloc] initWithImage:image];
CIFilter *filter = [CIFilter filterWithName:name];
[filter setValue:inputImage forKey:kCIInputImageKey];
CIImage *result = [filter valueForKey:kCIOutputImageKey];
CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];
UIImage *resultImage = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
return resultImage;
}
2、 調整圖片飽和度、亮度、對比度
/**
* 調整圖片飽和度, 亮度, 對比度
*
* @param image 目標圖片
* @param saturation 飽和度
* @param brightness 亮度: -1.0 ~ 1.0
* @param contrast 對比度
*
*/- (UIImage *)colorControlsWithOriginalImage:(UIImage *)image
saturation:(CGFloat)saturation
brightness:(CGFloat)brightness
contrast:(CGFloat)contrast{
CIContext *context = [CIContext contextWithOptions:nil];
CIImage *inputImage = [[CIImage alloc] initWithImage:image];
CIFilter *filter = [CIFilter filterWithName:@"CIColorControls"];
[filter setValue:inputImage forKey:kCIInputImageKey];
[filter setValue:@(saturation) forKey:@"inputSaturation"];
[filter setValue:@(brightness) forKey:@"inputBrightness"];
[filter setValue:@(contrast) forKey:@"inputContrast"];
CIImage *result = [filter valueForKey:kCIOutputImageKey];
CGImageRef cgImage = [context createCGImage:result fromRect:[result extent]];
UIImage *resultImage = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
return resultImage;
}
3、 全屏截圖
//全屏截圖
+ (UIImage *)shotScreen{
UIWindow *window = [UIApplication sharedApplication].keyWindow;
UIGraphicsBeginImageContext(window.bounds.size);
[window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
4、 截取一張 view 生成圖片
//截取view生成一張圖片
+ (UIImage *)shotWithView:(UIView *)view{
UIGraphicsBeginImageContext(view.bounds.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
5、 截取view中某個區域生成一張圖片
//截取view中某個區域生成一張圖片
+ (UIImage *)shotWithView:(UIView *)view scope:(CGRect)scope{
CGImageRef imageRef = CGImageCreateWithImageInRect([self shotWithView:view].CGImage, scope);
UIGraphicsBeginImageContext(scope.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect rect = CGRectMake(0, 0, scope.size.width, scope.size.height);
CGContextTranslateCTM(context, 0, rect.size.height);//下移
CGContextScaleCTM(context, 1.0f, -1.0f);//上翻
CGContextDrawImage(context, rect, imageRef);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRelease(imageRef);
CGContextRelease(context);
return image;
}
6、判斷是否為gif/png圖片的正確姿勢
//假設這是一個網絡獲取的URL
NSString *path = @"http://pic3.nipic.com/20090709/2893198_075124038_2.gif";
// 判斷是否為gif
NSString *extensionName = path.pathExtension;
if ([extensionName.lowercaseString isEqualToString:@"gif"]) {
//是gif圖片
} else {
//不是gif圖片
}
什么難道你不是這么判斷的么 ? 哦~ 我懂了, 難道你使用字符串截取來判斷的嗎 ? 哈哈開個玩笑!
以上判斷看似是可以的,但是這不嚴謹的, 在不知道圖片擴展名的情況下, 如何知道圖片的真實類型 ? 其實就是取出圖片數據的第一個字節, 就可以判斷出圖片的真實類型那該怎么做呢如下:
//通過圖片Data數據第一個字節 來獲取圖片擴展名
- (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;
}
7、設置圖片圓角?
//cornerRadius 設置為self.iconImage圖片寬度的一半(圓形圖片)
self.iconImage.layer.cornerRadius = 20;
self.iconImage.layer.masksToBounds = YES;
在此之后建議大家盡量不要這么設置, 因為使用圖層過量會有卡頓現象, 特別是弄圓角或者陰影會很卡, 如果設置圖片圓角我們一般用繪圖來做:
/** 設置圓形圖片(放到分類中使用) */
- (UIImage *)cutCircleImage {
UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0);
// 獲取上下文
CGContextRef ctr = UIGraphicsGetCurrentContext();
// 設置圓形
CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
CGContextAddEllipseInRect(ctr, rect);
// 裁剪
CGContextClip(ctr);
// 將圖片畫上去
[self drawInRect:rect];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
UILabel修改行距,首行縮進
1.UILabel修改文字行距,首行縮進
lineSpacing: 行間距
firstLineHeadIndent：首行縮進
font: 字體
textColor: 字體顏色
－ (NSDictionary *)settingAttributesWithLineSpacing:(CGFloat)lineSpacing FirstLineHeadIndent:(CGFloat)firstLineHeadIndent Font:(UIFont *)font TextColor:(UIColor *)textColor{
//分段樣式
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
//行間距
paragraphStyle.lineSpacing = lineSpacing;
//首行縮進
paragraphStyle.firstLineHeadIndent = firstLineHeadIndent;
//富文本樣式
NSDictionary *attributeDic = @{
NSFontAttributeName : font,
NSParagraphStyleAttributeName : paragraphStyle,
NSForegroundColorAttributeName : textColor
};
return attributeDic;
}
