UITextView+Extension分类功能：
1、提供占位文字，占位文字颜色、限制字符长度，和右下角提示字符输入数等属性可根据需求进行设置。
2、提供文本内容发生改变时的回调
效果图如下:
image.png
引入UITextView+Extension后，调用示例为：
-(UITextView *)tview{
if (!_tview) {
_tview = [[UITextView alloc]initWithFrame:CGRectMake(50, 100, ScreenW-100, 150)];
_tview.layer.cornerRadius = 5;
_tview.placeholderStr = @"最多输入10个字";
_tview.maximumLimit = 10;
_tview.font = [UIFont systemFontOfSize:15];
_tview.placeholderColor = UIColor.grayColor;
_tview.characterLengthPrompt = true;
_tview.backgroundColor = [UIColor hexColor:@"f5f5f5"];
}
return _tview;
}
[self.view addSubview:self.tview];
[self.tview textDidChange:^(NSString *textStr) {
NSLog(@"正在输入...%@",textStr);
}];
UITextView+Extension.h代码：
@interface UITextView (Extension)
/**
* 占位文字
*/
@property (nonatomic, copy) NSString *placeholderStr;
/**
* 占位文字颜色
*/
@property (nonatomic, strong) UIColor *placeholderColor;
/**
* 最大显示字符限制(会自动根据该属性截取文本字符长度)
*/
@property (nonatomic, assign) NSInteger maximumLimit;
/**
* 右下角字符长度提示(需要设置maximumLimit属性)，与占位文本颜色、字号一致 默认NO
*/
@property (nonatomic, assign) BOOL characterLengthPrompt;
/**
* 文本发生改变时回调
*/
- (void)textDidChange:(void(^)(NSString *textStr))handle;
/**
* 处理系统输入法导致的乱码,如果调用了maximumLimit属性，内部会默认处理乱码
*/
- (void)fixMessyDisplay;
@end
UITextView+Extension.m代码:
#import "UITextView+Extension.h"
#include <objc/runtime.h>
#import "NSString+Extension.h"
@interface UITextView ()
@property (nonatomic, assign) BOOL addNoti;
@property (nonatomic, copy) NSString *lastTextStr;
@property (nonatomic, copy) void(^textHandle) (NSString *textStr);
@end
@implementation UITextView (Extension)
- (void)setAddNoti:(BOOL)addNoti {
objc_setAssociatedObject(self, &@selector(addNoti), [NSNumber numberWithBool:addNoti], OBJC_ASSOCIATION_ASSIGN);
}
- (BOOL)addNoti {
BOOL obj = [objc_getAssociatedObject(self, &@selector(addNoti)) boolValue];
return obj;
}
- (void)setPlaceholderStr:(NSString *)placeholderStr {
objc_setAssociatedObject(self, &@selector(placeholderStr), placeholderStr, OBJC_ASSOCIATION_COPY_NONATOMIC);
// setNeedsDisplay会在下一个消息循环时刻，调用drawRect:
[self addTextChangeNoti];
[self setNeedsDisplay];
}
- (NSString *)placeholderStr {
NSString *obj = objc_getAssociatedObject(self, &@selector(placeholderStr));
return obj;
}
- (void)setPlaceholderColor:(UIColor *)placeholderColor {
objc_setAssociatedObject(self, &@selector(placeholderColor), placeholderColor, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
// setNeedsDisplay会在下一个消息循环时刻，调用drawRect:
[self addTextChangeNoti];
}
- (UIColor *)placeholderColor {
UIColor *obj = objc_getAssociatedObject(self, &@selector(placeholderColor));
return obj;
}
- (void)setMaximumLimit:(NSInteger)maximumLimit {
objc_setAssociatedObject(self, &@selector(maximumLimit), [NSNumber numberWithInteger:maximumLimit], OBJC_ASSOCIATION_ASSIGN);
//setNeedsDisplay会在下一个消息循环时刻，调用drawRect:
[self addTextChangeNoti];
[self setNeedsDisplay];
}
- (NSInteger)maximumLimit {
id obj = objc_getAssociatedObject(self, &@selector(maximumLimit));
return [obj integerValue];
}
- (void)setCharacterLengthPrompt:(BOOL)characterLengthPrompt {
objc_setAssociatedObject(self, &@selector(characterLengthPrompt), [NSNumber numberWithBool:characterLengthPrompt], OBJC_ASSOCIATION_ASSIGN);
//setNeedsDisplay会在下一个消息循环时刻，调用drawRect:
[self addTextChangeNoti];
[self setNeedsDisplay];
}
- (BOOL)characterLengthPrompt {
id obj = objc_getAssociatedObject(self, &@selector(characterLengthPrompt));
return [obj boolValue];
}
- (void)setTextHandle:(void (^)(NSString *))textHandle {
objc_setAssociatedObject(self, &@selector(textHandle), textHandle, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
- (void (^)(NSString *))textHandle {
id handle = objc_getAssociatedObject(self, &@selector(textHandle));
if (handle) {
return (void(^)(NSString *textStr))handle;
}
return nil;
}
- (void)setLastTextStr:(NSString *)lastTextStr {
objc_setAssociatedObject(self, @selector(lastTextStr), lastTextStr, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
- (NSString *)lastTextStr {
return [NSString emptyStr:objc_getAssociatedObject(self, _cmd)];
}
- (void)textDidChange:(void (^)(NSString *))handle {
self.textHandle = handle;
[self addTextChangeNoti];
}
- (void)fixMessyDisplay {
if(self.maximumLimit <= 0) {self.maximumLimit = MAXFLOAT;}
[self addTextChangeNoti];
}
/**
* 监听文字改变
*/
- (void)textDidChange {
//重绘
[self characterTruncation];
[self setNeedsDisplay];
}
- (void)setFont:(UIFont *)font {
// setNeedsDisplay会在下一个消息循环时刻，调用drawRect:
[self setNeedsDisplay];
}
- (void)drawRect:(CGRect)rect {
//设置文字属性
NSMutableDictionary *attributes = [NSMutableDictionary dictionary];
attributes[NSFontAttributeName] = self.font;
attributes[NSForegroundColorAttributeName] = self.placeholderColor ? self.placeholderColor : [UIColor lightGrayColor];
CGFloat x = 5;
CGFloat y = 8;
CGFloat width = rect.size.width -2 * x;
//画最大字符文本,添加文本显示边界
if((self.maximumLimit > 0) && (self.characterLengthPrompt == YES)) {
[self setContentInset:UIEdgeInsetsMake(0, 0, 25, 0)];
NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
paragraphStyle.alignment = NSTextAlignmentRight;
NSMutableDictionary *maximumLimitAttributes = [attributes mutableCopy];
maximumLimitAttributes[NSParagraphStyleAttributeName] = paragraphStyle;
NSString *limitStr = [NSString stringWithFormat:@"%lu/%ld",(unsigned long)self.text.length > (long)self.maximumLimit ? (long)self.maximumLimit : (unsigned long)self.text.length ,(long)self.maximumLimit];
[limitStr drawInRect:CGRectMake(x, rect.size.height-20+self.contentOffset.y, width, 20) withAttributes:maximumLimitAttributes];
}
//如果不需要显示最大字符限制文本，则把边界置为默认
else {
[self setContentInset:UIEdgeInsetsZero];
}
// 如果有输入文字，就直接返回，不画占位文字
if (self.hasText) return;
//画文字
CGFloat height = rect.size.height - 2 * y;
CGRect placeholderRect = CGRectMake(x, y, width, height);
[self.placeholderStr drawInRect:placeholderRect withAttributes:attributes];
}
- (void)characterTruncation {
//字符截取
if(self.maximumLimit) {
UITextRange *selectedRange = [self markedTextRange];
//获取高亮部分
UITextPosition *position = [self positionFromPosition:selectedRange.start offset:0];
//没有高亮选择的字，则对已输入的文字进行字数统计和限制,如果有高亮待选择的字，则暂不对文字进行统计和限制
if ((position == nil) && (self.text.length > self.maximumLimit)) {
const char *res = [self.text substringToIndex:self.maximumLimit].UTF8String;
if (res == NULL) {
self.text = [self.text substringToIndex:self.maximumLimit - 1];
}else{
self.text = [self.text substringToIndex:self.maximumLimit];
}
}
}
if((self.textHandle) && (![self.text isEqualToString:self.lastTextStr])) {
self.textHandle(self.text);
}
self.lastTextStr = self.text;
}
- (void)addTextChangeNoti {
if(self.addNoti == NO) {
// 当UITextView的文字发生改变时，UITextView自己会发出一个UITextViewTextDidChangeNotification通知
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textDidChange) name:UITextViewTextDidChangeNotification object:nil];
}
self.addNoti = YES;
}
- (void)dealloc {
if(self.addNoti == YES) {
[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidChangeNotification object:nil];
}
}
@end
